Compare straight-line and declining balance depreciation methods for UK business assets. Use the calculator, view worked examples and understand how accounting depreciation differs from HMRC capital allowances.
The main difference is timing: straight-line spreads cost evenly, while declining balance charges more depreciation in the early years.
Straight-line depreciation spreads an asset's depreciable cost evenly across its useful life. If a machine costs £20,000, has a residual value of £2,000 and is expected to last five years, the business records £3,600 of depreciation each year. This method is simple, predictable and easy to explain in accounts.
Declining balance depreciation, also called reducing balance depreciation, applies a fixed percentage to the remaining book value each year. The annual charge is larger at the start and smaller later. This can better reflect assets that lose value quickly early on, such as vehicles, IT equipment, tools, machinery and technology-heavy assets.
Both methods can be acceptable for UK accounting when they reflect the pattern in which the asset's economic benefits are consumed. The best choice depends on asset type, useful life, management judgement, accounting policy and how closely the method reflects real-world value loss.
The key tax point is separate: choosing a depreciation method for your accounts does not automatically decide your tax deduction. In UK tax computations, depreciation is usually added back and replaced with capital allowances. That is why this page separates the accounting calculator from the HMRC-style capital allowance estimate.
Compare both methods, calculate each one separately, or estimate a simple HMRC-style allowance schedule.
Here is how a £20,000 asset with £2,000 residual value compares over five years.
The annual charge stays the same every year. This makes budgeting, management accounts and profit reporting easier to understand.
The charge is larger at the start because it applies to the opening book value. Later charges fall as the carrying amount reduces.
| Year | Straight-Line Charge | Straight-Line Book Value | Declining Balance Charge | Declining Balance Book Value |
|---|---|---|---|---|
| 2026 | £3,600 | £16,400 | £5,000 | £15,000 |
| 2027 | £3,600 | £12,800 | £3,750 | £11,250 |
| 2028 | £3,600 | £9,200 | £2,812.50 | £8,437.50 |
| 2029 | £3,600 | £5,600 | £2,109.38 | £6,328.12 |
| 2030 | £3,600 | £2,000 | £1,582.03 | £4,746.09 |
A side-by-side comparison for UK accounting decisions.
| Factor | Straight-Line Depreciation | Declining Balance Depreciation |
|---|---|---|
| Annual charge | Same amount each year. | Higher in early years, lower later. |
| Formula | (Cost − residual value) ÷ useful life. | Opening book value × depreciation rate. |
| Best fit | Assets giving steady benefit each year. | Assets losing value or usefulness quickly early on. |
| Typical assets | Furniture, fixtures, leasehold improvements, some equipment. | Vehicles, computers, machinery, tools, technology. |
| Profit impact | Smoother profit and loss charge. | Lower early profits, higher later profits. |
| Book value pattern | Falls evenly to residual value. | Falls quickly first, then more slowly. |
| Tax impact | Accounting method only; HMRC capital allowances are separate. | Accounting method only; conceptually similar to WDA but separate. |
Select the method that best reflects how the asset is used and consumed.
Use straight-line when the asset gives fairly even benefits. Use declining balance when the asset is most productive or valuable in early years.
Apply the same method consistently to similar assets. Do not use one method for one laptop and a different method for another identical laptop.
Keep a note of useful life, residual value and method chosen. This supports year-end accounts, audit queries and internal reviews.
Use capital allowances for tax planning. Accounting depreciation and tax relief rarely match exactly, especially after 2026 rate changes.
A practical summary for business owners, bookkeepers and finance teams.
Straight-line works well when an asset delivers similar economic benefit each year. It is common because it is easy to calculate, easy to budget and easy to explain.
Declining balance works well when value, productivity or usefulness falls faster in the early years. It gives a more conservative book value early on.
For UK tax, commercial depreciation is normally disallowed and replaced with capital allowances. This creates a difference between accounting profit and taxable profit.
This is the most important difference for UK businesses.
Accounting depreciation is used to show a fair expense in your profit and loss account and a sensible carrying value on the balance sheet. It is based on management's estimate of useful life, residual value and the pattern in which the asset's benefit is consumed.
HMRC capital allowances are different. They are tax relief rules set by legislation. In many cases, a business adds back accounting depreciation in the tax computation and then deducts the relevant capital allowance instead. This means your accounts and tax return can show different numbers for the same asset.
The difference is especially important in 2026 because the main pool Writing Down Allowance rate changed to 14%, while the Annual Investment Allowance remains a major planning route for many businesses. Companies may also have access to full expensing on qualifying new and unused plant and machinery, while a 40% first-year allowance can apply to qualifying expenditure from 1 January 2026.
Helpful context when comparing accounting depreciation and tax relief.
AIA can allow 100% relief on qualifying plant and machinery up to the annual limit. It is often the simplest route for smaller businesses.
The main rate of Writing Down Allowance changed from 18% to 14% from April 2026 for relevant tax purposes.
Special rate assets such as integral features and some long-life assets are typically relieved more slowly.
Companies can claim full expensing on qualifying new and unused plant and machinery, subject to restrictions.
Most errors come from mixing accounting, cash flow and tax concepts.
The first mistake is assuming declining balance always saves tax sooner. It may reduce accounting profit earlier, but UK tax relief is based on capital allowances, not accounting depreciation. If you claim AIA or full expensing, the tax result can be completely different from either accounting method.
The second mistake is forgetting residual value. Straight-line depreciation normally uses cost less residual value. Declining balance usually applies a rate to the current book value and may not naturally reach the intended residual value unless the policy includes a final adjustment.
The third mistake is changing methods casually. A business should not swap methods simply to improve reported profit. A change should reflect a better estimate of how the asset's benefits are consumed and should be documented properly.
The final mistake is treating every asset the same. Computers, tools, furniture, vehicles and building fixtures often have different useful lives and value patterns. A good depreciation policy groups similar assets and applies a consistent, sensible method to each class.
Use this table as a starting point for choosing an accounting policy.
| Asset Type | Common Method | Why |
|---|---|---|
| Office furniture | Straight-line | Often provides steady use over several years. |
| Computers and laptops | Declining balance or short straight-line life | Technology value and usefulness can fall quickly. |
| Plant and machinery | Depends on usage | Heavy early use may support declining balance; steady production may support straight-line. |
| Company vehicles | Declining balance or carefully estimated straight-line | Vehicles usually lose value faster in early years. |
| Leasehold improvements | Straight-line | Often spread over lease term or useful life. |
The total depreciation may be similar over the life of the asset, but the yearly profit pattern can look very different.
Straight-line depreciation creates a stable expense pattern. This is useful where management wants the accounts to show an even cost of using the asset each year. It also makes management accounts easier to compare because the same annual charge appears repeatedly until the asset reaches its residual value.
Declining balance depreciation creates a more cautious early-year result. The first year depreciation charge is usually higher, so profit is lower in the first period after purchase. Later, as the carrying value falls, the annual charge becomes smaller. This can match assets that become less productive, less valuable or more outdated as they age.
The balance sheet also changes. Under straight-line depreciation, the asset carrying value falls in a straight path. Under declining balance depreciation, the carrying value falls faster at the start and then slows down. This can be useful for assets where resale value drops quickly in the first few years, such as company cars, laptops, tools and some specialist machinery.
Neither method changes cash flow by itself. Depreciation is a non-cash accounting charge. The cash left the business when the asset was bought, financed or paid for. Depreciation only spreads that cost through the accounts so the profit and loss account better reflects the period in which the asset is used.
Use this checklist before setting or reviewing a UK fixed asset depreciation policy.
Decide how long the asset is expected to provide economic benefit to the business. Useful life is not always the same as physical life; a laptop may still work after five years but no longer be useful for business systems.
Estimate what the asset may be worth at the end of its useful life. Straight-line depreciation normally uses this figure directly. Declining balance policies may need an end-of-life adjustment.
Apply the same policy to similar assets. A consistent approach improves comparability and reduces confusion when year-end accounts are reviewed by managers, lenders or accountants.
Keep a separate schedule for capital allowances. Your accounting depreciation schedule should not be treated as the tax calculation unless your accountant has confirmed the treatment.
The same £20,000 asset can produce very different accounting and tax figures.
| Approach | Year 1 Deduction / Charge | Purpose | Important Note |
|---|---|---|---|
| Straight-line accounting | £3,600 if depreciated over 5 years with £2,000 residual value | Reports the cost of using the asset in the accounts | Used for accounting profit, not automatically tax relief |
| Declining balance accounting | £5,000 if using a 25% reducing balance rate | Reflects faster early economic consumption | Still an accounting estimate, not an HMRC allowance |
| AIA tax allowance | Potentially £20,000 if eligible and within the limit | Calculates taxable profit relief | Eligibility and exclusions must be checked |
| Main pool WDA | £2,800 at 14% on £20,000 | Relieves qualifying pool expenditure over time | Applies to tax pools, not individual accounting schedules |
Different businesses often choose different depreciation policies because their assets behave differently.
A small marketing agency may use straight-line depreciation for office furniture and monitors because those assets provide steady use for several years. It might use a shorter useful life or reducing balance method for laptops because technology becomes outdated quickly and replacement cycles are frequent.
A construction business may prefer declining balance for tools, plant and site equipment that work hardest in the first few years and suffer heavy wear. Some heavy plant may still suit straight-line depreciation if it is maintained carefully and used steadily across long contracts.
A delivery or sales business with vans and cars may use declining balance because vehicles normally lose value fastest in early years. However, for tax, cars, vans and commercial vehicles can have different capital allowance rules, so the accounting policy and the tax claim should be reviewed separately.
A landlord or hospitality business may use straight-line depreciation for fixtures, fittings, furniture and refurbishments because the benefit is usually spread across the lease term or expected refurbishment cycle. If an asset is replaced after a fixed period, straight-line is often easier to support.
For most businesses, the right answer is not one universal method. The best policy is practical, consistent, documented and easy to reconcile with the fixed asset register. Review useful lives at year end, especially when assets are sold early, replaced sooner than expected or kept in use longer than originally planned.
Related calculators and official guidance for asset accounting and capital allowances.
Common questions about depreciation methods for UK businesses in 2026.