Annual Investment Allowance (AIA) 2026/27— How Businesses Claim 100% Tax Relief

What Is the Annual Investment Allowance?

The Annual Investment Allowance is a 100% first-year capital allowance available to all UK businesses on qualifying plant and machinery expenditure, up to a specified annual limit. The current limit is £1,000,000 per year, permanently set since April 2023.

Without AIA, plant and machinery purchases would be written down at 18% per year (main pool) or 6% per year (special rate pool) on a reducing balance — meaning a £100,000 machine might take 10–15 years to be fully relieved. AIA accelerates this to a single year.

AIA is available to: sole traders, partnerships (including LLPs), and limited companies. It applies to both UK and overseas businesses with a UK permanent establishment.

What Qualifies for AIA?

AIA applies to most plant and machinery used wholly or partly in a business. Broadly, this includes anything that is not a building, structure or land:

Qualifying assets (examples)

• Machinery: lathes, presses, CNC machines, production equipment
• Commercial vehicles: vans, lorries, trucks, tractors, forklifts
• Office equipment: computers, servers, printers, phones
• Furniture and fixtures in commercial premises
• Integral features: electrical systems, heating, air-conditioning, lifts
• Software (most off-the-shelf software and some bespoke)

Assets that do NOT qualify for AIA

• Cars (these have their own CO2-based treatment)
• Land and buildings (SBA at 3%/year applies to commercial structures)
• Assets acquired for leasing to others (with narrow exceptions)
• Gifts and donated assets

Full Expensing for Limited Companies

From 1 April 2023, limited companies that pay Corporation Tax can claim Full Expensing— a permanent 100% first-year allowance on new main-rate plant and machinery with no annual cap. This was introduced to encourage business investment and matches the immediate deduction that the US and some other countries offer.

A company buying £5 million of new machinery in one year can claim the full £5 million as a deduction against Corporation Tax profits in that year via Full Expensing — with no AIA cap restriction.

Writing-Down Allowances (WDA)

Where AIA does not apply (for excess expenditure above the £1 million AIA limit, cars, or assets excluded from AIA), the reducing balance Writing-Down Allowance applies:

• Main pool (18%): Most plant and machinery, including vans, equipment, and most commercial vehicles. The pool balance carried forward reduces by 18% each year.
• Special rate pool (6%): Integral features of buildings (electrical, heating, lifts), long-life assets (expected useful life over 25 years), thermal insulation.
• Single asset pools:Used for assets with mixed private and business use (e.g. a sole trader's car used partly privately). Each asset is kept separate so the business-use percentage can be applied accurately.

When an asset in the main or special rate pool is sold, the proceeds are deducted from the pool balance. If the pool goes negative, a balancing charge applies (taxable income). If the pool balance is very small after deducting disposal proceeds, a balancing allowance can be claimed to write off the remainder.

Structures and Buildings Allowance (SBA)

Commercial buildings do not qualify for AIA or WDA, but a separate 3% straight-line allowance — the Structures and Buildings Allowance — is available on the cost of constructing, converting or renovating qualifying commercial structures.

SBA covers: offices, factories, retail premises, warehouses, hotels (commercial), car parks. It does not cover: residential properties, the cost of land, or assets that qualify for other capital allowances.

SBA is at 3% per year on the original qualifying cost (not reducing balance). The allowance runs for 33.3 years. When the building is sold, the buyer inherits the remaining SBA period rather than starting fresh. The seller's final disposal is a balancing adjustment.

Capital Allowances for Cars

Cars have their own rules based on CO2 emissions at the time of first registration:

Cars with any private use by the owner (sole traders and partnerships) must be kept in a single asset pool, not pooled with other assets. The WDA is then restricted to the business-use percentage. For example, a 70% business-use car in the special rate pool gets 6% × 70% = 4.2% effective relief per year.

AIA for Sole Traders vs Limited Companies

The AIA limit and qualifying assets are broadly the same for sole traders and limited companies, but there are some key differences:

• Full Expensing: Only available to limited companies paying Corporation Tax. Sole traders and partnerships rely on AIA for 100% deductions.
• Tax saving rate: A sole trader in the 40% income tax band saves 40p per £1 of AIA claimed. A company paying 25% Corporation Tax saves 25p per £1. This means AIA is proportionally more valuable for higher-rate taxpayers who are sole traders.
• Accounting period: AIA is allocated to accounting periods, not tax years. A sole trader with a March year-end gets AIA for April to March. A company with a December year-end gets it for January to December. If a period is less than 12 months, the AIA limit is proportionally reduced.
• Associated businesses: If two businesses are under common control (e.g. same sole trader or same director), the AIA must be shared between them. The total available is still £1 million, split between the businesses as agreed.

Timing Strategies to Maximise Relief

Because AIA gives 100% relief in the accounting period of purchase, the timing of capital expenditure can significantly affect your tax position:

• Buy early in the accounting period: A purchase made on the first day of your accounting period gives relief 12 months earlier than a purchase on the last day. Both give 100% relief, but the former reduces tax 12 months sooner.
• Match large purchases to high-profit years: If you expect profits to be higher in one year (e.g. a one-off contract), bring forward capital purchases into that year to maximise the tax saving at the highest rate.
• Avoid straddling year-ends: If you place an order before your year-end but delivery and invoicing slip to the next period, the AIA claim falls in the next period. Confirm delivery and invoice dates carefully.
• Use AIA on special-rate assets first: If you have both main-rate assets and integral features, use AIA on the integral features first (they would otherwise only attract 6% WDA), and let main-rate assets fall into the 18% pool.

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