Annual Investment Allowance (AIA) is one of the most valuable capital allowances available to UK property investors and landlords. It allows you to claim 100% tax relief on qualifying plant and machinery costs in the year you buy them, up to an annual limit.

For the 2025/26 tax year, the AIA limit is £1 million for most businesses. This means you can deduct the full cost of qualifying assets from your taxable profits immediately, rather than spreading the relief over several years through writing down allowances.

This guide explains what AIA is, how it works for landlords and property investors, what qualifies, and what does not. We also cover the key restrictions you need to know before claiming.

How Does Annual Investment Allowance Work?

AIA gives you 100% tax relief on qualifying capital expenditure in the accounting period you incur it. If you spend £50,000 on qualifying equipment, you can deduct the full £50,000 from your taxable profits that year.

The allowance applies to most plant and machinery used in your property business. This includes fixtures in rental properties, equipment for maintenance, and certain building improvements.

Without AIA, you would claim capital allowances at a lower rate, typically 18% or 6% per year on a reducing balance basis. AIA accelerates the relief significantly.

The £1 million limit is a temporary measure introduced in 2019 and extended several times. It is currently confirmed until 31 March 2026. After that, the limit is due to revert to £200,000, though this could change in future budgets.

What Qualifies for AIA for Landlords?

To qualify for AIA, the expenditure must be on plant and machinery used in your property business. For landlords, this typically includes:

  • Fixtures in rental properties such as boilers, heating systems, air conditioning, lifts, and electrical systems
  • Kitchen and bathroom fittings including cookers, fridges, washing machines, and sanitaryware
  • Furniture and furnishings for furnished properties
  • Tools and equipment used for property maintenance
  • Fire alarm systems, security systems, and CCTV
  • Solar panels and other energy-saving installations
  • Office equipment used for managing your property portfolio

The asset must be new and unused when you buy it. Second-hand assets do not qualify for AIA, though you can still claim writing down allowances on them.

What Does Not Qualify for AIA?

Several types of expenditure are specifically excluded from AIA. These include:

  • Cars, these have separate capital allowance rules
  • Land and buildings, the structure itself does not qualify
  • Assets used partly for non-business purposes, you must apportion the claim
  • Assets given to you or inherited, AIA only applies to purchased assets
  • Expenditure incurred before the asset is brought into use

Buildings themselves do not qualify for AIA. However, integral features within buildings, such as electrical systems, water systems, and heating, can qualify as plant and machinery.

AIA for Furnished Holiday Lettings

Before April 2025, furnished holiday lettings (FHLs) qualified for full capital allowances including AIA. The FHL regime was abolished from 6 April 2025, which changed the rules significantly.

From April 2025, properties previously treated as FHLs are now taxed as standard rental businesses. This means capital allowances, including AIA, are no longer available for plant and machinery in those properties.

If you owned FHL properties before April 2025, you may have unrelieved capital allowance pools. These can still be claimed against future rental income, but no new AIA claims can be made for assets in those properties after the abolition date.

For serviced accommodation that qualifies as a trade rather than property income, different rules apply. You should speak to a specialist property accountant to determine your correct tax treatment.

AIA for Property Companies

If you hold your property portfolio through a limited company, AIA works slightly differently. Companies claim capital allowances, including AIA, through the corporation tax return.

The £1 million AIA limit applies to the company, not to each property. If you own multiple properties through one company, the limit covers all qualifying expenditure across the portfolio.

Property companies can also claim AIA on fixtures in commercial properties. This is particularly valuable for landlords converting commercial buildings to residential use or fitting out commercial units.

For companies with profits above £250,000, the main corporation tax rate of 25% applies. AIA at 100% relief means every £1,000 of qualifying spend saves £250 in tax for a company paying the main rate.

If you are considering incorporating your property portfolio, read our complete guide to buy-to-let limited companies for more detail on the tax implications.

AIA and Section 24 Restrictions

Section 24 restricts mortgage interest relief for individual landlords to a basic rate tax credit. This does not directly affect capital allowances, but it changes how you calculate your taxable profits.

Capital allowances, including AIA, are deducted from rental income before the Section 24 restriction applies. This means claiming AIA reduces your rental profits, which in turn reduces the amount of mortgage interest you cannot deduct.

For higher-rate taxpayers, claiming AIA can be particularly valuable because it reduces the income that would otherwise be taxed at 40% or 45%.

Our complete guide to Section 24 tax relief explains how capital allowances interact with the mortgage interest restriction.

How to Claim AIA

You claim AIA through your tax return. For individual landlords, this means including the claim in your self-assessment tax return. For companies, the claim goes in the corporation tax return.

You need to identify the qualifying expenditure and calculate the AIA claim for each accounting period. The claim is entered in the capital allowances section of the return.

If your qualifying expenditure exceeds the AIA limit for the period, the excess can be claimed through writing down allowances at 18% or 6% per year.

You must keep detailed records of the assets you purchase, including invoices, dates of purchase, and evidence of when the assets were brought into use. HMRC may ask for this information if they review your return.

For complex claims, particularly those involving fixtures in buildings, you may need a capital allowances specialist to prepare a valuation report. This is common for larger property portfolios.

AIA Limits and Timing

The AIA limit depends on your accounting period. For most businesses, the limit is £1 million per 12-month period. If your accounting period is shorter or longer, the limit is proportionally adjusted.

The £1 million limit applies to periods ending on or before 31 March 2026. For periods straddling the change date, you need to apportion the limit between the two rates.

For example, if your accounting period runs from 1 July 2025 to 30 June 2026, part of the period falls under the £1 million limit and part under the lower limit. HMRC provides detailed rules for calculating the transitional limit.

If the limit reverts to £200,000 from April 2026, you will need to plan your capital expenditure carefully to maximise relief within the lower cap.

Common Mistakes Landlords Make with AIA

Many landlords miss out on AIA because they do not realise what qualifies. Common errors include:

  • Not claiming AIA on fixtures in newly purchased rental properties
  • Assuming all building improvements qualify, only plant and machinery does
  • Forgetting to claim for office equipment used to manage the portfolio
  • Claiming AIA on second-hand assets, which do not qualify
  • Not keeping proper records of qualifying expenditure

Another common mistake is confusing repairs with capital expenditure. Repairs are deductible in full as revenue expenses, while capital expenditure qualifies for AIA or other capital allowances. Getting this distinction wrong can lead to HMRC enquiries.

Our complete list of landlord tax deductions covers the difference between repairs and capital expenditure in detail.

AIA vs Other Capital Allowances

AIA is not the only capital allowance available. Other allowances include:

  • Writing down allowances, 18% per year on main pool assets, 6% on special rate pool assets
  • First-year allowances, available for certain energy-efficient and environmentally beneficial assets
  • Structures and buildings allowance, 3% per year on qualifying building costs

AIA is generally the most generous because it gives 100% relief in year one. However, it is capped at £1 million per year. For very large capital expenditure programmes, you may need to use a combination of allowances.

Structures and buildings allowance (SBA) is separate from AIA. SBA gives 3% straight-line relief on the cost of constructing or renovating commercial buildings. It does not qualify for AIA because it covers the building structure, not plant and machinery.

Planning Your AIA Claims

If you are planning significant capital expenditure, timing your purchases can maximise your AIA relief. Consider these strategies:

  • Group purchases into one accounting period to stay within the £1 million limit
  • If your limit is lower, spread purchases across multiple periods
  • Claim AIA on the highest-value assets first
  • Use writing down allowances for assets that do not qualify for AIA

For portfolio landlords, it is worth reviewing your capital expenditure plans each year. A property accountant can help you structure your claims to minimise your tax liability.

If you are selling a property that has had AIA claimed on fixtures, you may need to adjust the capital allowances pool. This is known as a disposal event and can create a balancing charge or allowance.

Non-Resident Landlords and AIA

Non-resident landlords can claim AIA on the same basis as UK-resident landlords, provided the property business is within the charge to UK tax.

If you are a non-resident landlord using the Non-Resident Landlord (NRL) scheme, you can still claim capital allowances. The claim reduces your rental profits, which in turn reduces the tax withheld by your letting agent or tenant.

You should submit an NRL1 form to HMRC to receive rent without tax deducted. This allows you to account for capital allowances through your self-assessment return.

For non-resident companies owning UK property, AIA claims are made through the corporation tax return. The same £1 million limit applies.

Our property tax services cover both resident and non-resident landlords, including capital allowances planning.

Making Tax Digital and AIA Records

From 6 April 2026, Making Tax Digital (MTD) for Income Tax becomes mandatory for landlords with gross property income over £50,000. This means you must keep digital records and submit quarterly updates to HMRC.

Your AIA claims will need to be recorded digitally and reported through MTD-compatible software. You should start preparing your record-keeping systems now if you are affected.

The threshold drops to £30,000 from April 2027 and £20,000 from April 2028. Most portfolio landlords will be within MTD within the next few years.

Read our guide to MTD for landlords for more information on the requirements and deadlines.

Getting Professional Advice

AIA can save you significant tax, but the rules are detailed and mistakes can be costly. If you are planning capital expenditure on your property portfolio, it is worth getting professional advice.

A property accountant can review your expenditure plans, identify qualifying assets, and ensure your claims are correct. They can also help with capital allowances valuations for fixtures in properties.

For complex portfolios, particularly those involving commercial property, HMOs, or mixed-use developments, specialist advice is essential. The cost of professional advice is itself tax-deductible.

Contact our team to discuss your property tax situation and how AIA can benefit your portfolio.