Tag: accounting basics

Depreciation Methods Explained: Straight-Line vs Reducing Balance

When a business buys a piece of equipment, a vehicle, or any other long-term asset, that cost doesn’t hit the income statement all at once. It would distort the financials completely — one terrible month followed by years of apparent profitability with no corresponding cost. Instead, accounting spreads the cost of the asset across its useful life through a process called depreciation. But how that cost is spread matters enormously, and the method you choose affects your profit figures, your tax position, and the carrying value of your assets on the balance sheet every single year.

What Is Depreciation?

Depreciation is the systematic allocation of the cost of a tangible fixed asset over its expected useful life. It recognises that assets wear out, become obsolete, or lose value over time — and it matches that loss of value to the accounting periods in which the asset is being used to generate income. This is the matching principle at work.

When you buy a delivery van for £24,000, you don’t expense £24,000 in year one. Instead, you capitalise it on the balance sheet as a non-current asset and then depreciate it gradually, charging a portion of the cost to the income statement each year as a depreciation expense.

Depreciation is not a cash flow — it’s a non-cash accounting entry. The money left the business when the asset was purchased. Depreciation simply recognises, period by period, that the asset is being consumed in the process of generating revenue.

Two values matter in depreciation calculations: the cost of the asset (what you paid for it) and the residual value (the estimated amount you’ll receive when you dispose of it at the end of its useful life). The difference between these two figures — the depreciable amount — is what you spread over the asset’s useful life.

The Straight-Line Method

The straight-line method is the simplest and most widely used approach. It allocates an equal amount of depreciation in every accounting period across the asset’s useful life. The annual charge never changes — it is the same in year one as it is in the final year.

The formula is straightforward:

Annual depreciation = (Cost − Residual value) ÷ Useful life in years

Using the delivery van example — cost £24,000, residual value £4,000, useful life 4 years:

Annual depreciation = (£24,000 − £4,000) ÷ 4 = £5,000 per year

Each year, £5,000 is charged to the income statement as a depreciation expense, and the net book value (NBV) of the van on the balance sheet falls by £5,000. After four years, the van sits on the balance sheet at its residual value of £4,000 and is fully depreciated.

The straight-line method is favoured for assets that provide roughly equal benefit throughout their lives — office furniture, fixtures and fittings, leasehold improvements, and most plant and machinery fall into this category.

The Reducing Balance Method

The reducing balance method — also called the declining balance method — applies a fixed percentage rate to the asset’s net book value at the start of each period, rather than to its original cost. Because the NBV falls each year, the depreciation charge also falls each year, producing a front-loaded pattern of expense that is heavier in the early years and lighter later on.

The formula is:

Annual depreciation = Net book value at start of period × Depreciation rate %

Using the same van at a 25% reducing balance rate:

Year 1: £24,000 × 25% = £6,000 depreciation → NBV £18,000
Year 2: £18,000 × 25% = £4,500 depreciation → NBV £13,500
Year 3: £13,500 × 25% = £3,375 depreciation → NBV £10,125
Year 4: £10,125 × 25% = £2,531 depreciation → NBV £7,594

Notice that the reducing balance method never technically reaches zero — or even the residual value — purely through the formula. In practice, businesses either adjust the final year’s charge or switch to straight-line in the last period to bring the asset down to its residual value.

The reducing balance method suits assets that are more productive and more valuable in their early years — vehicles, computers, and technology equipment all tend to lose more of their economic value in the first few years of use than in later years.

Worked Example — Fernwood Interiors Ltd

Fernwood Interiors Ltd purchases a delivery van on 1 January for £24,000. The expected useful life is 4 years and the estimated residual value is £4,000. The table below shows the depreciation charge and net book value under both methods across the full useful life.

Year	Straight-Line Charge (£)	Straight-Line NBV (£)	Reducing Balance Charge (£)	Reducing Balance NBV (£)
Start	—	24,000	—	24,000
Year 1	5,000	19,000	6,000	18,000
Year 2	5,000	14,000	4,500	13,500
Year 3	5,000	9,000	3,375	10,125
Year 4	5,000	4,000	2,531	7,594
Total depreciated	20,000	4,000 ✓	16,406	7,594

The straight-line method depreciates the full depreciable amount (£20,000) exactly, landing precisely on the residual value of £4,000. The reducing balance method at 25% has depreciated £16,406 over four years — the van still carries an NBV of £7,594 at year end, above its estimated residual value. Fernwood’s accountant would adjust the rate or the final year’s charge to align the NBV with the expected disposal proceeds.

The key takeaway from this table: reducing balance front-loads the depreciation charge. In years one and two, the income statement carries a higher expense under reducing balance — which lowers reported profit in those early years but results in lower charges later when the asset is older and perhaps more prone to maintenance costs.

Which Method Should You Use?

The choice of depreciation method should reflect how the asset actually loses value and how evenly it contributes to generating revenue over its life. There is no single correct answer — it depends on the type of asset and the accounting standards your business follows.

Under UK GAAP (FRS 102) and IFRS, businesses must apply a depreciation method that reflects the pattern of consumption of the asset’s economic benefits. In practice, most UK SMEs default to straight-line for simplicity, while businesses with significant vehicle fleets or technology assets often use reducing balance to better match the reality of how those assets depreciate in the real world.

For tax purposes in the UK, the rules are different. HMRC does not allow businesses to deduct accounting depreciation as a tax expense. Instead, capital allowances — specifically the Annual Investment Allowance (AIA) and Writing Down Allowances (WDAs) — govern how much of a capital purchase can be deducted for tax. The WDA rates (currently 18% for the main pool and 6% for special rate assets) broadly follow a reducing balance approach. This means your accounting depreciation and your tax relief will rarely match exactly in any given year, creating temporary timing differences on your tax computation. For a full breakdown of how capital and revenue expenditure interact with tax, see our guide on capital vs revenue expenditure.

Once you’ve chosen a method for a class of asset, consistency matters. Switching depreciation methods between periods is permitted under accounting standards but requires disclosure in the financial statements and must be justified as providing more reliable and relevant information. Frequent switches are a red flag for auditors and will raise questions about whether the change is economically justified or cosmetically motivated.

How Depreciation Appears in the Financial Statements

Depreciation touches three of your key financial statements, and understanding where it appears in each is important for reading your accounts accurately.

On the income statement, depreciation appears as an operating expense — usually within administrative expenses or cost of sales, depending on the nature of the asset. It reduces your operating profit and your net profit for the period.

On the balance sheet, fixed assets are shown at cost less accumulated depreciation — that figure is the net book value. The longer you’ve held an asset and the faster it depreciates, the lower its NBV relative to its original cost. See our guide to understanding the balance sheet for how non-current assets are presented.

On the cash flow statement (indirect method), depreciation is added back to operating profit in the reconciliation section. Because it is a non-cash charge — no money actually left the business in the period — it must be reversed out of profit to arrive at the true cash generated from operations.

Key Takeaways

Depreciation spreads the cost of a fixed asset across its useful life, matching the expense to the periods in which the asset generates income.
The straight-line method charges an equal amount each year — simple, predictable, and suited to assets that provide even benefit over time.
The reducing balance method charges a fixed percentage on the declining net book value — front-loading the expense and better reflecting how some assets (vehicles, technology) lose value rapidly in early years.
The choice of method should reflect how the asset is actually consumed, not what produces the most convenient profit figure.
Depreciation is a non-cash item — it reduces profit but has no direct impact on your bank balance in the period it is charged.
For tax purposes in the UK, capital allowances (not accounting depreciation) determine how much of a capital purchase is deductible — these figures will rarely match your accounting charge.

Related reading: If you found this guide useful, you may also want to read our posts on capital vs revenue expenditure, understanding the balance sheet, trial balance explained, and understanding the income statement.

August 17, 2026

What Is a Trial Balance? A Clear Guide for Small Business Owners

Every set of books has a moment of reckoning — the point where you check whether everything you’ve recorded actually adds up. That moment is the trial balance. It’s one of the most important steps in the accounting cycle, yet it’s often misunderstood or skipped entirely by small business owners who rely on software to do the maths for them. Understanding what a trial balance is, how it works, and what it can and can’t tell you is a fundamental part of knowing whether your financial records are in good shape.

What Is a Trial Balance?

A trial balance is a summary of all the balances in your general ledger at a specific point in time, arranged into two columns: debits on the left and credits on the right. If your double-entry bookkeeping has been done correctly, the two columns must always add up to the same total. That equality is the whole point.

The name comes from an older accounting tradition — you were literally “trialling” (testing) whether your books balanced before preparing the final financial statements. Today it sits at the heart of the accounting cycle, acting as a checkpoint between your daily transaction recording and the production of your income statement and balance sheet.

A trial balance doesn’t tell you whether your accounts are correct — it tells you whether they balance. That’s a crucial distinction, and one every business owner should understand.

A trial balance lists every account in your chart of accounts — assets, liabilities, equity, income, and expenses — alongside its closing debit or credit balance. Every pound, dollar, or unit of currency entered as a debit somewhere must appear as a credit somewhere else. If the two columns don’t match, there is a bookkeeping error that must be found and corrected before financial statements can be produced.

How to Prepare a Trial Balance

Preparing a trial balance is a straightforward process once you have your ledger accounts up to date. Most accounting software will generate one automatically, but understanding the manual steps helps you interpret what you’re looking at.

Step 1 — Close off each ledger account. For every account in your general ledger, calculate the net balance. If debits exceed credits in an account, it has a debit balance. If credits exceed debits, it has a credit balance.

Step 2 — List every account. Set up a three-column schedule: account name, debit balance, and credit balance. Every account gets one row. An account only ever appears in one column — never both.

Step 3 — Know which column each account type belongs in. Assets and expenses normally carry debit balances. Liabilities, equity, and income normally carry credit balances. Contra accounts (such as accumulated depreciation or an allowance for doubtful debts) sit in the opposite column to their parent account.

Step 4 — Total both columns. Add up the debit column and the credit column separately. If the totals agree, your books balance for that period. If they don’t, you have at least one error to find.

Step 5 — Investigate any difference. A difference that is divisible by 9 often indicates a transposition error (e.g. entering £364 as £346). A difference that is exactly double a known figure often means a single entry was posted twice — or not at all — on one side.

Worked Example — Oakfield Trading Ltd

Oakfield Trading Ltd is a small wholesale business at the end of its first month of trading. The bookkeeper has posted all transactions and now prepares the trial balance to check whether the ledger is in order before producing the month-end income statement and balance sheet.

Account	Debit (£)	Credit (£)
Cash at bank	14,200
Trade receivables	8,500
Inventory	6,300
Office equipment	4,000
Accumulated depreciation — equipment		400
Trade payables		5,200
Bank loan		10,000
Share capital		12,000
Retained earnings		0
Sales revenue		22,400
Cost of goods sold	11,800
Rent expense	2,100
Wages expense	2,700
Depreciation expense	400
TOTAL	£50,000	£50,000

Both columns total £50,000. The ledger balances. Oakfield’s bookkeeper can now proceed with confidence to prepare the income statement (using the revenue and expense accounts) and the balance sheet (using the asset, liability, and equity accounts).

Notice that accumulated depreciation appears in the credit column even though it relates to an asset. It is a contra-asset account — it offsets the gross value of the office equipment rather than being listed separately as a debit. This is normal treatment and one of the areas that most often confuses people new to trial balances.

The Three Types of Trial Balance

The term “trial balance” doesn’t always refer to the same document. There are three distinct versions, each used at a different stage of the period-end process.

Unadjusted trial balance. This is the trial balance produced directly from the ledger before any period-end adjustments are made. It captures the raw balances as posted throughout the period — but it won’t yet reflect accruals, prepayments, depreciation charges, or provisions. This is your starting point.

Adjusted trial balance. Once all period-end adjustments have been journalled and posted — accrued expenses, prepaid costs, depreciation, and so on — you produce an adjusted trial balance. This version gives a more accurate picture of the business’s financial position and is the document used to prepare the final financial statements. If you’re unfamiliar with accruals and prepayments, our guide on accruals and prepayments explained covers the adjusting entries in detail.

Post-closing trial balance. After the financial statements have been produced and the temporary accounts (income and expenses) have been closed off to retained earnings, a final trial balance is prepared. This confirms that only permanent accounts — assets, liabilities, and equity — remain open going into the next period. It acts as the opening position for the new reporting cycle.

What a Trial Balance Won’t Catch

A balanced trial balance is a good sign, but it is not a guarantee of accuracy. There are several categories of error that leave both columns perfectly equal despite the underlying records being wrong.

Errors of omission. If a transaction is simply not recorded at all — neither the debit nor the credit — both columns remain equal. The trial balance won’t flag it.

Errors of commission. If a transaction is posted to the wrong account but the correct side — for example, rent expense debited to wages expense — the columns still balance. You’ve posted to the right type of account (both are expenses) but to the wrong one specifically.

Compensating errors. If two separate mistakes cancel each other out — one overstatement and one understatement of equal amounts — the trial balance will appear balanced despite two underlying errors.

Errors of principle. Posting a capital expenditure to the income statement as a revenue expense is a classic example. The debit and credit are technically correct, but the accounting treatment violates the principle of how capital items should be handled. The trial balance has no way of detecting this.

For multi-entity businesses, the challenge is compounded — a balanced trial balance in each subsidiary doesn’t mean the consolidated group position is clean. BrizoConsol’s guide on how to prepare for audit with consolidated financials covers the additional layer of checks required when combining trial balances across multiple entities.

Trial Balance vs Balance Sheet

A common point of confusion is the difference between a trial balance and a balance sheet. They contain overlapping information, but they serve very different purposes.

The trial balance includes every account — assets, liabilities, equity, income, and expenses — in one comprehensive list. It is an internal working document, not a formal financial statement. It is used by accountants and bookkeepers to verify the ledger before producing anything external.

The balance sheet, by contrast, includes only the permanent accounts — assets, liabilities, and equity — and presents them in a structured format designed to be read by stakeholders. Income and expense accounts don’t appear on the balance sheet; their net result flows through to retained earnings. The balance sheet is a formal financial statement. The trial balance is the step that comes before it.

Key Takeaways

A trial balance lists every general ledger account balance in debit and credit columns. If total debits equal total credits, your books balance for the period.
It is produced at three stages: unadjusted (before period-end entries), adjusted (after accruals and prepayments), and post-closing (after income and expense accounts are closed).
A balanced trial balance does not mean your records are error-free — it only means there are no unmatched debit/credit postings. Errors of omission, commission, and principle can all hide within a balanced trial balance.
The trial balance is an internal working document. It feeds into the income statement and balance sheet but is not itself a formal financial statement.
In most accounting software, a trial balance is generated automatically — but understanding it manually helps you interpret results, spot anomalies, and troubleshoot discrepancies when they arise.

Related reading: If you found this guide useful, you may also want to read our posts on double-entry bookkeeping explained, understanding the balance sheet, accruals and prepayments explained, and understanding the income statement.

August 14, 2026

Double-Entry Bookkeeping Explained: How Journal Entries Keep Your Accounts in Balance

Every number in every set of accounts — whether for a sole trader, a growing SME, or a listed corporation — was put there by a journal entry. Double-entry bookkeeping is the language accountants use to record financial events, and it has been in continuous use since the Italian merchants of the fifteenth century first formalised it. Understanding how it works does not require a degree in accounting. What it requires is grasping one simple idea: every transaction affects two accounts, always, and the two effects must balance. Get comfortable with that principle, and the entire structure of accounting becomes logical rather than mysterious.

What Is Double-Entry Bookkeeping?

Double-entry bookkeeping is a system in which every financial transaction is recorded as two equal and opposite entries — one debit and one credit — in different ledger accounts. The name comes from the fact that each transaction is entered twice: once on the debit side of one account, and once on the credit side of another.

This is not an arbitrary accounting convention. It reflects economic reality. When a business buys a van for cash, two things happen simultaneously: the business gains an asset (the van) and loses an asset (the cash). Recording both sides of this exchange is what makes the books balance. If you only recorded the van arriving but not the cash leaving, your accounts would be out of balance — and the discrepancy would be the first sign something was wrong.

The result of this system is that the total of all debits always equals the total of all credits. This self-balancing property is one of accounting’s most powerful error-detection mechanisms. When a trial balance — the summary of all account balances — does not balance, it signals immediately that an error has been made somewhere in the entries.

Debits and Credits: The Golden Rules

The single most common source of confusion in bookkeeping is the meaning of “debit” and “credit”. In everyday language, a debit means money going out of your bank account; a credit means money coming in. In double-entry bookkeeping, the words mean something more specific and often counterintuitive to beginners.

In accounting, every ledger account belongs to one of five categories: assets, liabilities, equity, income, or expenses. The rule for debits and credits is different depending on the category:

Account Type	A Debit…	A Credit…	Example Account
Asset	Increases the balance	Decreases the balance	Cash, Trade Debtors, Vehicles
Liability	Decreases the balance	Increases the balance	Bank Loan, Trade Creditors, VAT Payable
Equity	Decreases the balance	Increases the balance	Share Capital, Retained Earnings
Income / Revenue	Decreases the balance	Increases the balance	Sales Revenue, Interest Received
Expense	Increases the balance	Decreases the balance	Wages, Rent, Depreciation

A useful memory aid is DEAD CLIC: Debits increase Expenses, Assets, and Drawings; Credits increase Liabilities, Income, and Capital. Once this table is memorised, any transaction can be broken down logically into its two sides without guesswork.

Debits and credits are not value judgements — “debit” does not mean “bad” and “credit” does not mean “good”. They are simply the left and right sides of every ledger account. Their effect — whether they increase or decrease a balance — depends entirely on the type of account they are applied to.

Journal Entries in Practice: A Worked Example

Birchwood Consultants Ltd is a small consultancy. In October, the following transactions occur. Let us record each as a double-entry journal entry.

Transaction 1: Owner invests £20,000 into the business

Account	Debit (£)	Credit (£)	Reason
Bank (Asset)	20,000		Cash received — asset increases
Share Capital (Equity)		20,000	Owner’s investment — equity increases

Transaction 2: Business pays £1,200 for office rent

Account	Debit (£)	Credit (£)	Reason
Rent Expense (Expense)	1,200		Cost incurred — expense increases
Bank (Asset)		1,200	Cash paid out — asset decreases

Transaction 3: Business invoices a client £5,000 for consulting work

Account	Debit (£)	Credit (£)	Reason
Trade Debtors (Asset)	5,000		Amount owed to us — asset increases
Consulting Revenue (Income)		5,000	Revenue earned — income increases

Transaction 4: Client pays the £5,000 invoice

Account	Debit (£)	Credit (£)	Reason
Bank (Asset)	5,000		Cash received — asset increases
Trade Debtors (Asset)		5,000	Debt cleared — asset decreases

After all four transactions, the total of all debit entries (£31,200) equals the total of all credit entries (£31,200). The books balance. This is double-entry working as intended.

From Journal Entries to Financial Statements

Journal entries do not live in isolation. They flow through a structured sequence that ultimately produces the financial statements every business relies on.

Each journal entry is first recorded in a journal (the book of original entry) in chronological order. The entries are then posted to individual ledger accounts — one account per category, such as “Bank”, “Rent Expense”, or “Trade Debtors”. Each ledger account is typically visualised as a T-account, with debits on the left and credits on the right, allowing the running balance to be tracked at a glance.

Periodically — usually at month-end — all ledger account balances are extracted into a trial balance. If the total of all debit balances equals the total of all credit balances, the bookkeeping is arithmetically correct. The trial balance then feeds directly into the preparation of the three core financial statements: the income statement (profit and loss), the balance sheet, and the cash flow statement.

This chain — from individual transaction to financial statement — is the same whether you are using a paper ledger, a spreadsheet, or modern accounting software like Xero or QuickBooks. The software automates the posting and trial balance, but every entry it makes follows the same double-entry logic. For businesses that operate across multiple entities, the same principle applies at the consolidation stage: group accountants must understand the underlying journal entries in each subsidiary in order to correctly eliminate intercompany transactions and produce accurate group accounts. BrizoConsol’s guide on delivering consolidated financials without the manual work explains how this aggregation process works in practice for multi-entity groups.

Common Journal Entry Types for SMEs

While every transaction is unique, most SME bookkeeping involves a relatively small set of recurring entry types. Becoming fluent with these covers the vast majority of day-to-day accounting:

Sales invoice raised: Debit Trade Debtors / Credit Sales Revenue
Customer payment received: Debit Bank / Credit Trade Debtors
Purchase invoice received: Debit Expense or Asset / Credit Trade Creditors
Supplier payment made: Debit Trade Creditors / Credit Bank
Wages paid: Debit Wages Expense / Credit Bank
Depreciation charged: Debit Depreciation Expense / Credit Accumulated Depreciation
Prepayment (e.g. insurance paid in advance): Debit Prepayment Asset / Credit Bank; then reverse monthly as expense accrues
Accrual (e.g. electricity bill not yet received): Debit Electricity Expense / Credit Accruals (Liability)
Loan received: Debit Bank / Credit Loan Liability
Dividend paid: Debit Retained Earnings / Credit Bank

The accruals and prepayments entries in particular are central to the accruals basis of accounting — the principle that income and expenses are recognised when they are earned or incurred, not simply when cash changes hands. This is what separates proper financial accounting from simple cashbook recording, and it is what makes financial statements meaningful for decision-making rather than merely a record of bank movements.

Key Takeaways

Double-entry bookkeeping records every transaction as two equal and opposite entries — a debit in one account and a credit in another.
Debits increase assets and expenses; credits increase liabilities, equity, and income. The mnemonic DEAD CLIC helps: Debits increase Expenses, Assets, Drawings; Credits increase Liabilities, Income, Capital.
The system is self-balancing: total debits always equal total credits. A trial balance that does not balance signals a bookkeeping error.
Journal entries flow through ledger accounts and a trial balance before becoming the income statement, balance sheet, and cash flow statement.
Most day-to-day SME bookkeeping involves ten or so recurring entry types. Mastering these covers the overwhelming majority of transactions a business will encounter.
Accounting software automates the posting and trial balance, but the underlying double-entry logic is identical — understanding it makes you a more confident and critical user of any accounting system.

Related reading: Double-entry bookkeeping is the mechanism that keeps the Accounting Equation (Assets = Liabilities + Equity) permanently in balance. The ledger accounts for assets and liabilities flow directly into the Balance Sheet, while income and expense accounts form the Income Statement. For a broader introduction to the discipline that connects all of these concepts, see our post on Accounting Made Simple.

June 15, 2026

Depreciation Methods Explained: Straight-Line, Reducing Balance and Beyond

Every piece of equipment, vehicle, and machine your business owns was worth more the day you bought it than it is today. This steady loss of value is not a flaw in your accounting — it is a fundamental principle called depreciation, and how you account for it directly affects your profit figure, your tax position, and the accuracy of your balance sheet. For SME owners and accountants alike, understanding the main depreciation methods — and knowing which one to apply — is one of the most practically useful skills in the accounting toolkit.

What Is Depreciation and Why Does It Matter?

When a business buys a long-term asset — a delivery van, a piece of machinery, a computer server — it does not expense the full cost in the year of purchase. Instead, it spreads that cost over the asset’s useful working life. This spreading of cost is depreciation.

There are two core reasons this matters. First, it gives a truer picture of profitability. If you expensed a £40,000 van in full the year you bought it, your profit that year would appear artificially low. By depreciating it over five years at £8,000 per year, each year’s accounts reflect the actual consumption of that asset’s value. Second, the accumulated depreciation reduces the carrying value of the asset on your balance sheet — keeping it aligned with economic reality rather than overstating what the business actually owns.

Depreciation is a non-cash expense. It reduces profit and therefore reduces the tax liability, but no cash leaves the business at the point the depreciation charge is recorded. Cash only left when the asset was originally purchased.

The Main Methods of Depreciation

There are three methods you will encounter most frequently in practice. Each produces a different pattern of annual charges, and each suits different types of asset.

1. Straight-Line Depreciation

The simplest and most widely used method. The asset loses the same fixed amount of value each year over its useful life.

Formula: Annual Depreciation = (Cost − Residual Value) ÷ Useful Life (years)

The residual value (sometimes called scrap value) is the estimated amount the asset will be worth at the end of its useful life. If an asset will be worthless at disposal, residual value is zero.

2. Reducing Balance Depreciation

Also called the declining balance method. The depreciation charge is calculated as a fixed percentage of the asset’s remaining book value each year — not its original cost. This means the charge is higher in early years and tapers off over time, which better reflects how many assets (especially technology and vehicles) lose value more quickly when new.

Formula: Annual Depreciation = Net Book Value at Start of Year × Depreciation Rate %

3. Units of Production (Activity-Based) Depreciation

Rather than spreading cost over time, this method ties depreciation to actual usage. It is best suited to assets whose wear is genuinely driven by how much they are used — a printing press, a quarry vehicle, or specialised manufacturing equipment.

Formula: Depreciation per Unit = (Cost − Residual Value) ÷ Estimated Total Units of Production
Annual Charge = Depreciation per Unit × Units Produced in the Year

Worked Example: Comparing the Three Methods

Ashford Printing Ltd purchases a digital press for £50,000. It has an estimated useful life of five years and a residual value of £5,000. In a typical year the press handles approximately 200,000 print runs; total estimated lifetime output is 1,000,000 print runs. The table below shows Year 1 and Year 3 charges under each method.

Method	Year 1 Charge (£)	Year 2 Charge (£)	Year 3 Charge (£)	Year 4 Charge (£)	Year 5 Charge (£)	Total (£)
Straight-Line (20%)	9,000	9,000	9,000	9,000	9,000	45,000
Reducing Balance (30%)	15,000	10,500	7,350	5,145	3,602	41,597*
Units of Production (200k/yr)	9,000	9,000	9,000	9,000	9,000	45,000

*Reducing balance at 30% leaves a residual book value of approximately £8,403 after five years. The rate would typically be set to bring the asset to its expected residual value — the figures above illustrate the pattern rather than an exact match.

Notice how the reducing balance method front-loads the expense: Ashford records a £15,000 charge in Year 1 versus £9,000 under straight-line. By Year 3, the reducing balance charge (£7,350) has dropped below the straight-line equivalent. This can have meaningful effects on reported profit — and therefore tax — in the early years of an asset’s life.

The depreciation method you choose does not change the total cost of the asset over its life — only the timing of when that cost hits your profit and loss account. Consistency and transparency in your chosen approach matter more than which method you pick.

Choosing the Right Method for Your Asset

No single method suits every asset. The key question is: how does this asset actually lose its value?

Use straight-line when the asset provides roughly equal benefit each year — office furniture, leasehold improvements, most computer equipment, and commercial property fixtures are good candidates. It is predictable, easy to explain to stakeholders, and administratively simple.

Use reducing balance for assets that decline in value rapidly when new — vehicles are the classic example. A van bought for £25,000 might lose £8,000 of market value in its first year, but only £3,000 in its fourth year. The reducing balance method aligns the accounting charge with this economic reality, producing a smoother match between the asset’s book value and its market value.

Use units of production for assets where utilisation, not time, is the primary driver of wear — heavy plant, specialist manufacturing tools, or mining equipment. If the machine sits idle for six months, no depreciation charge is recorded, which is a more accurate reflection of what happened economically.

Once chosen, the method should be applied consistently across similar asset classes and disclosed in the accounting policies note of your financial statements. Changing method without good reason raises questions with auditors and HMRC alike.

Depreciation, Residual Value, and Useful Life: The Key Estimates

Depreciation calculations rest on two estimates that require professional judgement: useful life and residual value. Both should reflect the business’s genuine expectations, not a default figure.

Useful life varies significantly by asset type. HMRC’s capital allowance rules provide a tax-focused view, but accounting depreciation and tax depreciation are separate concepts — a business may depreciate an asset over seven years for accounting purposes while claiming capital allowances under a different rate for tax. The difference creates timing differences that, in some cases, give rise to a deferred tax liability. (Our post on deferred tax covers this in detail.)

Residual value should be reviewed periodically. If market conditions change — for example, a particular model of vehicle loses value more rapidly than expected due to changing emissions regulations — the residual value estimate should be revised, and the remaining depreciation recalculated over the remaining useful life.

Depreciation treatment also varies depending on which accounting standards a business follows. Under IFRS (IAS 16), businesses have the option to revalue certain fixed assets to fair value and then depreciate from the revalued amount — a treatment not available under UK GAAP’s FRS 102. BrizoConsol’s comparison of IFRS vs UK GAAP key differences in financial reporting is a useful reference if your business is considering which framework applies, particularly for groups with international subsidiaries.

Common Depreciation Mistakes to Avoid

Applying a single method to all assets indiscriminately. A laptop and a quarrying truck have very different usage profiles. Using straight-line for everything is administratively convenient but may misrepresent the economics.
Setting residual value to zero by default. Many assets retain meaningful value at end of use — vehicles, specialist tools, and plant equipment are often sold secondhand. Ignoring residual value overstates the annual depreciation charge.
Forgetting to start depreciation in the month of acquisition. Some businesses depreciate a full year’s charge regardless of when an asset was bought. A pro-rata charge from the acquisition date is more accurate (and required under some standards).
Continuing to depreciate fully depreciated assets. Once an asset reaches its residual value, depreciation stops. A nil net book value asset that is still in use should be disclosed as such — not written down further.
Confusing accounting depreciation with tax depreciation (capital allowances). These are separate calculations. The accounting charge goes through your P&L; the capital allowance claim goes on your tax return. They rarely match in any given year.

Key Takeaways

Depreciation spreads the cost of a long-term asset over its useful life, matching the expense to the periods that benefit from the asset’s use.
The three main methods are straight-line (equal annual charge), reducing balance (front-loaded charge), and units of production (usage-based charge).
Method choice should reflect how the asset actually loses value — not simply default to the simplest option.
Two key estimates drive depreciation: useful life and residual value. Both require regular review.
Accounting depreciation and tax capital allowances are separate calculations — differences between them can create deferred tax positions.
Once chosen, apply your depreciation policies consistently and disclose them clearly in your financial statements.

Related reading: Depreciation appears as a line on your Income Statement and reduces the carrying value of assets on your Balance Sheet. When the timing difference between accounting depreciation and tax allowances creates a deferred tax balance, our guide to Deferred Tax Liability explains what that means and how it is recorded. For a broader overview of the financial frameworks your business may operate under, see our guide to IFRS.

June 12, 2026