The Annual Investment Allowance (AIA) is a capital allowance that lets businesses deduct the full cost of qualifying plant and machinery from their taxable profit in the year of purchase. In 2024/25, the AIA limit is £1,000,000 per year.
For most small businesses, the AIA means that buying business equipment gives you an immediate, full tax deduction in the year you spend the money, rather than spreading the deduction over several years. It is one of the most straightforward tax reliefs available and one of the most commonly underclaimed.
How the AIA Works
When a business buys a piece of equipment for business use, the cost is treated as capital expenditure rather than a direct expense. Normally, capital expenditure is deducted gradually over several years through writing down allowances. The AIA removes this restriction for most businesses, allowing the full cost to be deducted in the year of purchase.
Here is a simple example:
| Scenario | Without AIA | With AIA |
| Business buys equipment costing £20,000 | Deduct 18% per year: £3,600 year 1, £3,312 year 2, etc. | Deduct full £20,000 in year 1 |
| Tax saved at 19% Corporation Tax | £684 in year 1 | £3,800 in year 1 |
| Cash flow benefit | Small relief spread over many years | Immediate full relief in the year of purchase |
The AIA does not change how much tax relief you eventually receive over the asset’s lifetime. It changes when you receive it. For most businesses, getting the full deduction in year one is significantly more valuable than waiting.
What Qualifies for the AIA?
The AIA applies to most plant and machinery used in a business. Qualifying items include:
- Tools, equipment, and machinery used in the business
- Computers, laptops, tablets, and phones used for business
- Vans and lorries (not cars — see below)
- Office furniture and equipment
- Fixtures and fittings in commercial premises
- Agricultural machinery
- Building alterations needed to install qualifying plant
What does NOT qualify for AIA
- Cars (these receive writing down allowances instead, at 18% or 6% depending on CO2 emissions)
- Assets acquired through hire purchase where the item has not been brought into use
- Items bought in the final period of a business ceasing to trade
- Buildings, land, and structures (though integral features of buildings such as electrical systems and heating do qualify)
- Assets that will be leased to others
| Cars are excluded from AIAIf your business buys a car, it cannot claim AIA on it. Cars use a separate writing down allowance system: 18% per year for cars with CO2 emissions up to 50g/km, and 6% per year for higher-emission cars. Zero-emission cars qualify for a 100% First Year Allowance instead, which gives the same immediate full deduction as AIA. |
Who Can Claim the AIA?
The AIA is available to:
- Sole traders
- Partnerships (though special rules apply to partnerships with corporate partners)
- Limited companies
- Most other businesses liable to Income Tax or Corporation Tax
The £1,000,000 limit is per business, not per owner. If you own two separate businesses, each has its own £1,000,000 AIA. However, if two businesses are under common control, they may be treated as associated and share a single AIA limit.
AIA and the Tax Year: Timing Matters
The AIA applies to the accounting period in which the expenditure is incurred, not when the asset is ordered or delivered. This makes the timing of purchases important for tax planning.
If your company’s accounting year ends on 31 March and you are planning a significant equipment purchase, buying before 31 March brings the full deduction into the current year’s Corporation Tax return. Buying on 1 April means the deduction falls in the following year’s return, delaying your tax saving by a full year.
For businesses that are approaching or above the 25% Corporation Tax rate (profits above £250,000), accelerating equipment purchases into the current year saves tax at the higher rate. This is a legitimate and straightforward planning opportunity that many businesses miss.
AIA vs Writing Down Allowances: When WDA Applies
For expenditure above the £1,000,000 AIA limit, or for assets that do not qualify for AIA, writing down allowances (WDA) apply instead:
| Pool Type | WDA Rate | Applies To |
| Main pool | 18% per year (reducing balance) | Most plant and machinery not in special rate pool |
| Special rate pool | 6% per year (reducing balance) | Long-life assets, integral building features, thermal insulation, cars above 50g/km CO2 |
| Single asset pool | 18% or 6% per year | Assets with private use element or short life assets |
Writing down allowances use a reducing balance method, meaning you claim a percentage of the remaining pool value each year. This continues until the pool is fully written down or the asset is sold. For most small businesses operating within the £1,000,000 AIA limit, WDA is only relevant for cars.
How to Claim the AIA
The AIA is claimed on your tax return:
- Sole traders: claim on the self-employment pages of your Self Assessment return in the capital allowances section
- Limited companies: claim on the company’s Corporation Tax return (CT600) in the capital allowances section
- You do not need to keep separate AIA records, but you must be able to evidence the expenditure with receipts, invoices, or bank statements
Most accountancy software and tax return software includes capital allowance calculators that make the claim straightforward. If you use an accountant, they will claim the AIA as part of preparing your annual accounts and tax return.
Frequently Asked Questions
What is the Annual Investment Allowance limit for 2024/25?
The AIA limit is £1,000,000 per year in 2024/25. This means you can deduct up to £1,000,000 of qualifying plant and machinery costs from your taxable profit in a single year. The limit has been permanently set at £1,000,000 since April 2023.
Can a sole trader claim the Annual Investment Allowance?
Yes. The AIA is available to sole traders, partnerships, and limited companies. A sole trader claims it on the self-employment pages of their Self Assessment return. The same £1,000,000 limit applies regardless of business structure.
Can I claim AIA on second-hand equipment?
Yes. The AIA applies to both new and second-hand plant and machinery. It does not require the asset to be brand new. The full cost of qualifying second-hand equipment can be deducted in the year of purchase, subject to the annual limit.
What happens if my AIA claim exceeds my profit?
If your AIA claim creates or increases a loss, that loss can be carried forward and offset against future profits, carried back against previous years’ profits, or offset against other income in the same year depending on your business structure. An accountant can advise on the most efficient use of a loss created by a large AIA claim.
Can I claim AIA on assets I lease or hire purchase?
For hire purchase agreements, you can claim AIA when the asset is brought into use, not when you take out the agreement. For operating leases where you never own the asset, you cannot claim AIA — the lease payments are treated as a revenue expense instead.
Does the AIA apply to integral features of a building?
Yes. Integral features such as electrical systems, cold water systems, space and water heating systems, lifts, and external solar shading qualify for AIA. General building structure and land do not qualify. This distinction is important for businesses investing in fitting out commercial premises.
Make Sure You Are Claiming the Full AIA
M&B Tax Services prepares annual accounts and tax returns for businesses across the UK. We make sure every qualifying capital purchase is identified, the AIA is claimed in full, and your tax bill is minimised in the year you spend the money.
We are ICB-regulated accountants based in Rugby. Many businesses leave money on the table by missing AIA claims or claiming the wrong assets. A review of your capital expenditure often reveals unclaimed relief.
Book a free 30-minute call and we will review your capital allowance position at no cost.
Joanna Bruty
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