Capital Allowances: A Practical Guide for UK Accountants

Capital allowances are the way UK businesses get tax relief on money they spend on certain capital assets, such as equipment and machinery. They're a vital part of business tax, allowing the cost of qualifying assets to be set against taxable profits. This practical guide explains what capital allowances are, the main types, the current rates, and how they work — in plain language. It's a core area of UK tax for accountants and a key topic in corporation tax and ACCA study. (Capital allowances rules and rates change frequently — always confirm the current position on GOV.UK.)

What are capital allowances?

When a business buys an asset like a machine or computer, it can't simply deduct the cost as an everyday expense, because depreciation isn't an allowable deduction for tax. Instead, the tax system provides capital allowances — a defined way to deduct the cost of qualifying capital assets from taxable profits over time (or sometimes all at once). In effect, capital allowances are the tax equivalent of depreciation, but governed by tax rules rather than accounting judgement. They typically apply to "plant and machinery" — a broad category covering equipment, machinery, tools, computers, and certain fixtures.

The main types of capital allowance

There are several routes to relief, and the right one depends on the business and the asset. As confirmed by GOV.UK, the key allowances currently include:

• Annual Investment Allowance (AIA). A 100% deduction on qualifying plant and machinery up to £1 million a year — now a permanent limit. For most businesses, the AIA means the full cost of most equipment can be written off against profits in the year of purchase.
• Full expensing. A permanent 100% first-year allowance for companies investing in new main-rate plant and machinery, with an associated 50% first-year allowance for special-rate assets. This lets companies deduct the full cost immediately, with no upper limit.
• 40% first-year allowance. From 1 January 2026, a new permanent 40% first-year allowance for main-rate plant and machinery is available where full expensing doesn't apply — notably for unincorporated businesses and assets bought for leasing.
• Writing-down allowances (WDAs). Where an asset isn't fully relieved upfront, its cost is written down over time at a set percentage each year on a reducing-balance basis. The main pool rate is currently 14% a year, with a lower rate for "special rate" assets.

How capital allowances work in practice

In a typical claim, a business identifies its qualifying capital spending for the period, applies the most beneficial allowance (often the AIA or full expensing, giving immediate 100% relief), and pools any remaining expenditure to write down over future years via WDAs. The allowances are then deducted from taxable profits, reducing the tax bill. Because the rules — and especially the rates and limits — change regularly, getting the current position from GOV.UK or a tax adviser is essential before making decisions.

Why capital allowances matter

Capital allowances directly reduce a business's tax bill, so they're a significant factor in the real, after-tax cost of investing in assets. Generous allowances like full expensing and the AIA are designed to encourage business investment, and using them well can make a meaningful difference to a company's cash flow and tax position. For accountants, advising clients on capital allowances — what qualifies and which allowance to claim — is an important, value-adding part of tax work.

Why it matters for finance professionals

Capital allowances are a core part of UK business taxation and a frequently examined area in tax papers. Understanding the main allowances, the current rates and limits, and how to apply them is essential for anyone preparing tax computations or advising businesses. Because the rules change so often, the discipline of always checking the current position is itself part of the skill.

Frequently asked questions

What are capital allowances?

A form of tax relief that lets UK businesses deduct the cost of qualifying capital assets (mainly plant and machinery) from their taxable profits — the tax equivalent of depreciation, since depreciation itself isn't tax-deductible.

What is the Annual Investment Allowance?

A 100% deduction on qualifying plant and machinery up to £1 million a year (a permanent limit), letting most businesses write off the full cost of most equipment in the year of purchase.

What is full expensing?

A permanent 100% first-year allowance for companies investing in new main-rate plant and machinery, with no upper limit, plus a 50% first-year allowance for special-rate assets.

What are writing-down allowances?

The method of relieving an asset's cost over time at a set percentage each year on a reducing-balance basis — currently 14% a year for the main pool, with a lower rate for special-rate assets.

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