Annual Investment Allowance: Tax Relief on Business Equipment

The Annual Investment Allowance (AIA) allows businesses to deduct the full cost of qualifying plant and machinery from their taxable profits in the year of purchase. It's one of the most valuable tax reliefs available to UK businesses—and many leave money on the table simply by not understanding how it works.

Here's what qualifies, how to claim it, and how much you can save.

What Is the Annual Investment Allowance?

The AIA is a UK tax relief that gives you immediate deduction on capital spending. Instead of spreading the cost of equipment over multiple years (depreciation), you deduct the entire purchase price from your taxable profits in the year you buy it.

As of the 2026 tax year, the AIA limit is £1 million per year. Once you claim £1m in relief in a given tax year, additional purchases fall into the regular capital allowances system, which spreads relief over time. The limit resets on 6 April each year—unused allowance doesn't roll over.

This is a powerful relief. A business buying £600,000 of machinery could reduce its taxable profit to zero in that year, deferring a corporation tax bill of £150,000 (at the current 25% rate). For a self-employed trader in the higher-rate tax bracket, the same £600,000 spend could save £108,000 in income tax and National Insurance.

What Equipment Qualifies for AIA?

Not everything a business buys counts as plant and machinery. The concept of "plant" has been refined by decades of tax law and tribunal decisions. Here's what qualifies and what doesn't.

Qualifies for AIA:

Machinery and equipment (lathes, compressors, printing presses, production lines)
Computer hardware (servers, workstations—but not software licences)
Business vehicles (vans, lorries, specialised vehicles—but not standard cars)
Furniture and fittings that are removable (office desks, fitted shelving, kitchen equipment)
Tools and implements above a certain value
Manufacturing plant and tooling

Does not qualify:

Land and buildings (walls, roofs, integral structural elements)
Alterations to buildings that form part of the building (fitted kitchens integral to a listed property, for example)
Standard cars (these are handled under special capital allowance rules)
Software licences and patents (these may qualify for other reliefs, like R&D tax credits)
Stock and working capital
Leased equipment (unless you're the lessor claiming relief on the purchase cost)

The key test is: would the asset still exist independently of the building? A fitted office kitchen counts as plant. The brickwork does not.

For longer-term assets that fall outside AIA, see How to Calculate Depreciation for Business Assets.

How AIA Works: Examples and When the Limit Runs Out

Let's walk through a practical scenario.

Scenario: Small manufacturing business in 2026

You run a metalworking company with a taxable profit (before capital allowances) of £120,000. In January 2026, you buy:

CNC lathe: £80,000
Welding equipment: £25,000
Delivery van: £35,000
Total: £140,000

All three items qualify for AIA. You claim the full £140,000 in the 2025/26 tax year. Your taxable profit becomes £120,000 – £140,000 = –£20,000.

That's a trading loss of £20,000, which you can:

Carry forward to set against profits in future years
Claim back against other income in the same year (rental income, dividend income, salary from another role)
In limited circumstances, carry back one year

If you're a limited company at the 25% corporation tax rate, that loss saves you £5,000 in tax. If you're self-employed and a higher-rate taxpayer, it saves you £8,000 in income tax and National Insurance combined.

When you hit the £1m limit:

If you claim £1m in AIA in one tax year and buy another £300,000 of equipment, that extra £300,000 doesn't qualify for AIA. Instead, it goes into the regular capital allowances system:

General Pool (18% Writing Down Allowance) Most plant and machinery goes here. You claim 18% of the written-down value each year. So if your General Pool has £100,000, you claim £18,000 relief in year 1, then 18% of £82,000 (£14,760) in year 2, and so on. The relief is smaller each year, but you eventually get full relief.

Special Rate Pool (6% WDA) Energy-inefficient plant and some vehicles fall into this pool, where relief is much slower.

The trade-off is clear: AIA is faster relief, so it's worth planning purchases to maximise your £1m allowance each tax year.

Common Mistakes with AIA

Assuming everything counts as plant.

A newly fitted office with new desks, chairs, and integrated lighting might seem like it all qualifies. But if the lighting is hard-wired into the building, it's structural, not plant. Desks and chairs do count—they're removable. Ask: could this be removed without damaging the building?

Missing the expenditure deadline.

You claim AIA for the tax year in which you incur the cost, not necessarily when you use the equipment. If you buy a lathe on 5 April 2026, you can claim it for the 2025/26 year—even if you don't use it until June. However, certain assets must be brought into use within two years of the year of expenditure. If you're buying something unusual, check with your accountant.

Forgetting to record what you claim.

HMRC can enquire up to four years back (six if they suspect carelessness). Keep invoices, purchase orders, delivery notes, and evidence that equipment is used in the business. If you claim AIA on a "lathe" and an inspector asks what it's for, you'll need proof.

Not keeping equipment separate from building improvements.

A business refurbishing an office might mix plant (desks, air conditioning units) with building work (rewiring, replastering). If you claim AIA on everything as a lump sum, HMRC may disagree. Get your accountant to identify which items are plant before you claim.

Mixing AIA with other reliefs.

You can't claim the same cost twice. If you've claimed AIA on plant, you can't also claim R&D tax credits on the same item. Be clear about which relief you're using.

How to Claim the Annual Investment Allowance

If you're sole trader or partnership:

Calculate your capital expenditure (cost of purchases, less any sales or disposals)
Claim the appropriate amount on your self-assessment tax return in the capital allowances section
Your accountant usually handles this, or you can do it yourself via the online form
The claim reduces your taxable profit

If you're a limited company:

Your accountant prepares a capital allowances computation
Claim AIA as part of the corporation tax return (Form CT600)
Any amount over £1m goes into the capital allowance pools for future years
The deduction reduces your corporation tax bill

You don't need to notify HMRC separately—it's built into your tax return. But the claim must be accurate; HMRC does spot-check capital allowances.

AIA and Other Tax Reliefs

The UK offers several ways to get relief on business spending. Here's how AIA compares:

Relief	What it covers	Speed of relief	When to use
AIA	Plant and machinery	Full deduction year 1	Capital equipment: machinery, vehicles, tools
Capital allowances (WDA)	Plant and machinery	18% or 6% per year	Equipment over AIA limit
R&D tax credits	R&D costs	Cash credit or deduction	Development, testing, research
Business expenses	Staff, utilities, rent, training	Full deduction year 1	Day-to-day running costs
Pension contributions	Retirement savings	Deduction year 1	Personal/employee retirement
Working from home relief	Home office costs	£6/week or actual costs	Self-employed working from home

AIA is the fastest way to get relief on capital equipment, which is why it's so valuable. If you're a growing business investing in machinery, AIA should be your first port of call.

Frequently Asked Questions

Q: Does the unused AIA limit roll over to next year?

A: No. The £1m limit resets every tax year (6 April to 5 April). If you claim £600,000 in 2025/26, you get a fresh £1m in 2026/27. The unused £400,000 from 2025/26 is gone. Plan your major purchases accordingly.

Q: Can I claim AIA on a car?

A: Not on a standard saloon or estate car. Cars are handled under special capital allowance rules (Special Rate Pool, 6% WDA). However, a van, a specialised vehicle (ambulance, refrigerated delivery van), or a vehicle adapted for a disabled employee can qualify for AIA. The distinction is subtle—check with your accountant if you're unsure.

Q: What if I buy equipment and sell it later in the same year?

A: You claim AIA on the net cost. Buy a lathe for £50,000, sell it three months later for £40,000, and you claim AIA on £10,000 (the net loss). Buy for £50,000 and sell for £60,000, and you don't get AIA relief (though you may have a chargeable gain).

Q: Does AIA work on second-hand equipment?

A: Yes. It doesn't matter if the equipment is brand new or used. If it qualifies as plant and machinery and you haven't owned it before, you can claim AIA on the purchase cost.

Q: Can I claim AIA if my business made a loss?

A: Yes. If your trading profit is already negative and you claim AIA on top, your loss is larger. But you still benefit: the loss carries forward to future years or offsets other income (depending on your situation), and it doesn't expire. It's not wasted relief.

Q: Is there a minimum amount I need to spend to claim AIA?

A: No minimum. You can claim AIA on a single item if it qualifies. For very small items (under £500), it's often simpler to claim them as general business expenses, which achieves the same result without extra record-keeping.

Q: How does AIA interact with VAT?

A: AIA relief is based on the cost of the equipment. If you're VAT-registered, the cost is usually the amount excluding VAT (you reclaim the VAT separately as input tax). If you're not VAT-registered, the cost includes VAT, and you claim AIA on the full amount. Check your VAT position with our sales tax calculator.

Running Your Numbers

The actual tax saving from AIA depends on your personal tax rate (20%, 40%, or 45% if self-employed, or 25% corporation tax if a company). Use our sales tax calculator to model your position, and How to Calculate the ROI of a Business Investment to decide whether the investment itself makes commercial sense.

For more detail or if you're in any doubt about what qualifies, consult your accountant or check HMRC's guidance on capital allowances and plant and machinery.