UK Allowable Expenses & Capital Allowances for Companies (2025/26)

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UK business expenses and capital allowances are the everyday levers that determine a company’s taxable profit. This guide explains the ‘wholly and exclusively’ test for allowable expenses, the difference between revenue and capital costs, the Annual Investment Allowance, full expensing, and the disallowable items that catch businesses out.

What expenses can a company deduct?

A company can deduct revenue expenses incurred wholly and exclusively for the purposes of the trade — staff wages, rent, utilities, stock, professional fees, marketing, travel and many others. These reduce taxable profit pound for pound, lowering the corporation tax bill. The ‘wholly and exclusively’ test is the gateway: the expense must be for the business, not for private benefit.

The test is applied strictly. An expense with a dual purpose — part business, part personal — generally fails unless the business element can be clearly identified and apportioned. This is why directors must separate personal and company spending carefully, and why good bookkeeping that categorises every cost correctly is the foundation of an accurate, defensible corporation tax return.

What is the difference between revenue and capital expenditure?

Revenue expenditure is the day-to-day running cost of the business — consumed within the period and fully deductible against profit. Capital expenditure is spending on assets that provide lasting benefit, like machinery, vehicles or equipment. Capital costs aren’t deducted as ordinary expenses; instead, relief comes through capital allowances spread or accelerated according to the rules.

This distinction is fundamental and frequently misunderstood. Treating a capital purchase as a revenue expense overstates the deduction and understates tax; treating a revenue cost as capital does the reverse. The line can be subtle — a repair is usually revenue, but an improvement is often capital — and getting it right is essential to a correct return and to claiming the relief you’re entitled to.

What is the Annual Investment Allowance?

The Annual Investment Allowance (AIA) gives 100% first-year relief on up to £1 million of qualifying plant and machinery per year. This means a company can deduct the full cost of most equipment, tools, fixtures and commercial vehicles in the year of purchase, rather than spreading the relief over many years through writing-down allowances.

The AIA is one of the most valuable and accessible reliefs available. For a profitable company, timing a major equipment purchase before the year-end accelerates the deduction into the current period, reducing tax sooner. With a £1 million annual limit, it covers the capital spending of the vast majority of businesses entirely in the year they buy.

What is full expensing?

Full expensing allows companies to deduct 100% of the cost of qualifying new and unused plant and machinery in the year of purchase, with no upper limit, alongside a 50% first-year allowance for certain other assets. Made permanent to encourage business investment, it’s particularly valuable for larger companies whose capital spending exceeds the £1 million AIA cap.

Full expensing and the AIA together mean most companies can get immediate, full relief on their equipment investment. The rules on which assets qualify, and the treatment when assets are later sold, require care, but the headline benefit is powerful: qualifying capital investment can be written off entirely against profit in the year it’s made, sharply reducing the corporation tax due.

What expenses are disallowed?

Some costs are never deductible regardless of business purpose. Business entertainment — entertaining customers and contacts — is disallowed, as are most fines and penalties, costs of a capital nature treated incorrectly as revenue, and any expenditure with a private or non-trade purpose. Depreciation in the accounts is also added back and replaced by capital allowances.

These disallowable items are a common source of error because the expense is often genuinely commercial. Adding back entertainment, depreciation and other disallowed costs is a standard part of preparing the corporation tax computation from the accounts. Knowing what’s disallowed prevents over-claiming, which would otherwise lead to an understated tax bill and potential penalties on enquiry.

How do directors’ and staff costs work?

Salaries, employer pension contributions and most staff costs are deductible for corporation tax, making them an effective way to reduce profit while rewarding people. Employer pension contributions are especially useful, giving relief on the contribution while building the director’s or employee’s retirement fund — a frequent tool for managing profits near the corporation tax thresholds.

Director remuneration must be structured carefully, balancing the corporation tax deduction for salary against the income tax and National Insurance it triggers personally. This links directly to the salary-versus-dividend decision: salary reduces corporation tax but costs more in personal tax and NIC, while dividends do neither. Optimising this mix is central to owner-managed company tax planning.

A practical example: equipment purchase and the AIA

Suppose a company with £120,000 of profit buys £40,000 of new machinery before its year-end and claims the AIA. The full £40,000 is deducted, reducing taxable profit to £80,000. Because the company was in the marginal relief band, that £40,000 deduction saves tax at the 26.5% marginal rate on the relevant slice — a substantial reduction in the bill from a purchase the business needed anyway.

Had the company instead spread the relief over years, the tax saving would have been delayed and the cash-flow benefit diluted. The example shows how capital allowances, well-timed, convert necessary investment into immediate tax relief — and why understanding them is essential to managing both the corporation tax bill and the company’s cash position.

Maximising deductions while staying compliant

Good expense and capital allowance management means claiming everything you’re legitimately entitled to — all allowable costs, the AIA, full expensing, pension contributions — while correctly adding back disallowable items. The difference between thorough and careless treatment can be significant tax, but over-claiming invites assessment, so accuracy in both directions is the goal.

The foundation is good record-keeping that captures and correctly categorises every cost as revenue or capital, business or private, allowable or disallowed. Combined with sensible timing of capital purchases and pension contributions around the year-end, this turns routine bookkeeping into genuine tax efficiency — the everyday discipline that underpins a well-managed corporation tax position.

How do capital allowances work when you sell an asset?

When you sell or dispose of an asset on which you’ve claimed capital allowances, a balancing adjustment may arise. If you sell for more than the tax written-down value, a balancing charge adds to your taxable profit; if for less, a balancing allowance gives further relief. This ensures the total relief over the asset’s life matches its actual net cost to the business.

This matters most for assets given 100% relief through the AIA or full expensing, where the entire cost was deducted upfront. Selling such an asset can produce a taxable balancing charge equal to the sale proceeds. Understanding this prevents an unwelcome surprise on disposal and is part of planning capital purchases and sales with their full tax life cycle in mind.

How do home and vehicle costs work for companies?

Mixed-use costs need careful treatment. Where a director works from home, the company can reimburse a reasonable proportion of household costs or pay a flat allowance, deductible if genuinely for business. Company vehicles are more complex: the cost may attract capital allowances, but private use triggers a taxable benefit in kind on the director, often making company cars tax-inefficient unless electric.

Electric vehicles currently enjoy favourable benefit-in-kind rates and capital allowance treatment, which has made them a popular efficient choice for director cars. The interaction of capital allowances, benefit-in-kind charges and VAT on vehicles is intricate, and getting it right requires looking at the company and personal tax together — a recurring theme in owner-managed company planning.

Common expense and allowance mistakes to avoid

Typical errors include claiming private costs as business expenses, misclassifying capital spend as revenue (or vice versa), forgetting to add back disallowable items like entertainment and depreciation, and failing to claim the AIA or full expensing on qualifying purchases. Each distorts the tax bill and can invite an HMRC challenge.

Avoiding them rests on disciplined bookkeeping that categorises every cost correctly, a clear grasp of the revenue-versus-capital line, and a routine of claiming all legitimate allowances while adding back what’s disallowed. Done consistently, this both minimises tax within the rules and produces a return that withstands scrutiny — the dual goal of every well-run company’s tax process.

Building deductions into your financial routine

The companies that manage expenses and allowances best build the discipline into everyday operations: capturing every cost with its correct tax treatment, timing capital purchases around the year-end, and using pension contributions to manage profit near the thresholds. This continuous approach beats a year-end scramble to find deductions after the profit is already set.

Combined with good software and, where helpful, professional advice, this routine turns expense and allowance management into genuine tax efficiency. It ensures the company claims everything it’s entitled to, stays compliant, and uses the timing flexibility the rules allow — the everyday foundation on which a well-managed corporation tax position is built.

How do writing-down allowances work?

Not all capital spending gets 100% relief. Expenditure beyond the AIA and full-expensing rules, or on assets that don’t qualify for them, attracts writing-down allowances — a percentage of the asset’s value deducted each year on a reducing-balance basis. Assets are grouped into pools, with main-rate and special-rate pools carrying different percentages.

This spreads relief over several years rather than giving it all upfront, which matters for cash-flow and tax planning. While most businesses get immediate relief through the AIA, understanding writing-down allowances is important for larger capital programmes and for specific asset types like certain fixtures and higher-emission vehicles, ensuring the right rate of relief is claimed on each category of spend.

How do capital allowances support business investment?

Capital allowances exist partly to encourage businesses to invest in productive assets by giving tax relief on that spending. The generous AIA and full-expensing regimes mean a company investing in new equipment can often recover a quarter of the cost through reduced corporation tax in the same year, materially lowering the net cost of the investment.

For finance teams planning capital expenditure, factoring this relief into investment appraisals changes the picture: the after-tax cost of qualifying equipment is significantly lower than the sticker price. Timing purchases to capture relief in the most beneficial period, and understanding which assets qualify for which allowance, turns capital allowance planning into a genuine driver of efficient, well-timed business investment.

Frequently Asked Questions