Annual Investment Allowance Explained: A 2026 Small Business Guide

Buy a new van, a commercial oven or a set of laptops, and you would reasonably expect to knock the cost off your business profits before you are taxed on them. The Annual Investment Allowance (AIA) is the rule that lets you do exactly that — and usually all in one go, in the year you buy.

For most small businesses it is the single most useful capital allowance there is. Yet plenty of owners either forget to claim it, claim it in the wrong year, or never quite grasp why their accountant keeps asking when an asset was actually paid for. This guide clears that up.

This article is general information for UK small businesses, not tax advice. Allowances, limits and rules change, so check the current figures on GOV.UK or speak to a qualified accountant before making a decision based on tax.

What the Annual Investment Allowance actually is

When your business buys equipment it expects to use for several years — machinery, tools, computers, vans, fixtures — that spending is treated as capital expenditure rather than a day-to-day running cost. Normally you cannot simply expense capital items; instead you claim relief gradually through capital allowances.

The AIA short-circuits that. It lets you deduct 100% of qualifying expenditure from your taxable profits in the same accounting period, up to an annual limit. So if you buy a £12,000 machine and the AIA covers it in full, your taxable profit drops by £12,000 that year rather than over the next eight or ten.

The limit has been set at £1 million for some years now. That is far more headroom than the overwhelming majority of small firms will ever use, but always confirm the current threshold and how it interacts with your corporation tax position before you rely on it.

What equipment qualifies (and what does not)

The AIA covers most plant and machinery — a deceptively broad term in tax. In practice that includes:

• Tools, machines and manufacturing equipment
• Computers, servers, tablets and most office equipment
• Vans, lorries and other commercial vehicles
• Office furniture, shelving and shop fittings
• Some fixtures you install in a building, such as integral electrical or heating systems

A few important things do not qualify. Cars are the big one — they are excluded from the AIA entirely and have their own rules based on CO2 emissions. Buildings and land do not qualify either, nor do items you already owned personally and brought into the business, or things you were given. If you buy something part-business, part-personal, you can only claim the business-use proportion.

The AIA is not a discount on the price of equipment. It reduces the profit you pay tax on — so the real saving is the price multiplied by your tax rate.

How it cuts your tax bill: a worked example

Say you run a small limited company making, after costs, £60,000 profit before any equipment purchases. In March you spend £15,000 on new machinery that fully qualifies for the AIA.

Claim the AIA and your taxable profit falls to £45,000. If your effective corporation tax rate were, for example, 25%, the £15,000 deduction saves you £3,750 in tax. The kit still cost you £15,000 — but it is £3,750 cheaper after tax than it looks on the invoice.

For a sole trader the mechanics are similar, except the saving depends on your income tax band and National Insurance position rather than corporation tax. The principle holds: the higher your marginal rate, the more an AIA claim is worth.

AIA and full expensing: how they fit together

You may have heard about full expensing, which also gives 100% relief on qualifying plant and machinery. So why have both?

The key differences are who can use them and what they cover. Full expensing applies to companies paying corporation tax and has its own conditions, particularly around buying brand-new (not second-hand) assets. The AIA, by contrast, is open to sole traders, partnerships and companies alike, and it does cover used equipment. For many small companies the two overlap, and a good accountant will simply apply whichever gives the cleanest result. If you want the detail, see our companion guide on full expensing and capital allowances.

Timing your purchases to make the most of it

Because the AIA limit resets each accounting period, when you buy matters as much as what you buy. A few practical pointers:

• The date that counts is usually when you become committed to the cost, not when the item is delivered or when you finally pay. For most outright purchases that is the date of the contract or order.
• If you are near the end of your accounting year and planning a big purchase, bringing it forward a few weeks can pull the relief into the current year.
• Equally, if you have made a loss this year, you might prefer to delay a purchase so the relief lands when you actually have profits to set it against.

If you buy equipment specifically to deliver a public-sector contract, factor the timing in alongside the contract start date. You can search live UK tenders on Tendarix to see what is coming up and plan capital spending around the work you expect to win.

Funding the purchase without losing the relief

You do not have to pay cash to claim the AIA. Buy equipment on hire purchase and you can generally still claim the full allowance, because you are treated as the eventual owner. Leasing is different — with an operating lease you typically deduct the rental payments as an expense instead. If you are weighing up how to fund kit, our guide to asset finance and equipment leasing walks through the trade-offs, and it is worth keeping an eye on your broader allowable business expenses so nothing claimable slips through.

Common mistakes to avoid

• Trying to claim for a car. It feels like plant and machinery, but it is not eligible for the AIA.
• Claiming in the wrong period. Get the commitment date wrong and you can lose a year of relief.
• Forgetting the private-use restriction. A laptop you also use at home is only partly claimable.
• Overlooking second-hand kit. Used equipment usually qualifies for the AIA — do not assume you can only claim on new items.

Frequently asked questions

Can sole traders claim the Annual Investment Allowance?

Yes. The AIA is available to sole traders, partnerships and limited companies. For an unincorporated business the saving is calculated against your income tax and National Insurance rather than corporation tax, but the underlying relief works the same way.

What happens if I spend more than the AIA limit in a year?

Spending above the annual limit does not disappear — the excess simply moves into the normal capital allowances pools and attracts relief at the standard writing-down rates over future years. Given how high the limit is, very few small businesses ever reach it.

Do I have to claim the full AIA in one year?

No. You can claim part of the available allowance and carry the rest of the asset's value into the pools for later years. This can be useful if claiming the full amount would waste relief — for instance if it would push your profits below your tax-free allowances.

Capital allowances reward businesses that invest to grow, and the AIA is the most generous tool in the box for most small firms. If you are investing to take on bigger or public-sector work, browse live tenders on Tendarix to line up the contracts that justify the spend — then talk the timing through with your accountant before you buy.