Capital allowances allow you to deduct the cost of certain fixtures and integral features from your taxable profits. In an HMO conversion, a significant portion of the build cost may qualify.
Electrical systems, heating and hot water installations, cold water systems, and ventilation qualify as integral features. These attract an 8% annual writing-down allowance or can be claimed under the Annual Investment Allowance.
Fire alarm systems, emergency lighting, fire doors, fire-rated partitions, and sprinkler systems all qualify. In HMO conversions, fire safety work often represents a substantial claim.
Bathroom suites, fitted kitchens, carpets, curtains, and built-in furniture in lettable rooms. These fall under plant and machinery allowances at 18% writing-down rate.
Insulation, boiler upgrades, and certain energy-efficient systems may qualify under enhanced capital allowances, providing faster tax relief.
Structural work such as walls, roofs, foundations, and floors generally does NOT qualify for capital allowances. However, items embedded within the structure (e.g., wiring in walls, pipework under floors) often do qualify.
The claim process requires a specialist surveyor report and coordination with your accountant. Here is the typical workflow.
Instruct a capital allowances surveyor to inspect the property and review build costs
The surveyor produces a detailed report identifying qualifying expenditure and classifying items
Your accountant incorporates the claim into your self-assessment or corporation tax return
Claims can be made in the tax year the expenditure occurs, or retrospectively for prior years
Annual Investment Allowance (AIA) allows 100% first-year deduction on qualifying spend up to the AIA limit (currently £1 million)
Any spend above the AIA limit is added to the writing-down allowance pool at 18% (plant and machinery) or 8% (integral features)
Keep all invoices, contracts, and the surveyor report as supporting evidence in case of HMRC enquiry
The proportion of build cost that qualifies varies by project type. HMO conversions typically have a higher qualifying percentage than standard residential renovations because of the fire safety and communal area fit-out work involved.
| Project Type | Typical Qualifying % |
|---|---|
| Full house-to-HMO conversion | 20–35% of total build cost |
| HMO refurbishment (existing HMO) | 15–25% of total spend |
| New-build HMO | 15–20% of total build cost |
| Commercial-to-HMO conversion | 25–40% of total build cost |
On a £150,000 conversion with 25% qualifying, a higher-rate taxpayer could save approximately £15,000 in tax. Actual savings depend on your tax rate and whether you use the AIA or writing-down allowances.
You can technically make a capital allowances claim without a surveyor, but the two approaches produce very different results.
Your accountant estimates qualifying items from invoices. Simpler and cheaper but typically identifies only 30–50% of the full claim value. Higher risk of HMRC challenge without a formal report.
Best for: Small refurbishment projects under £30,000 where the surveyor fee would not be justified by the additional tax saving.
A qualified surveyor inspects the property, analyses build costs in detail, and produces an HMRC-compliant report. Identifies significantly more qualifying expenditure and provides robust evidence for your claim.
Best for: Any HMO conversion or refurbishment over £50,000. The surveyor fee (typically £1,500–£3,000) is itself tax-deductible and usually pays for itself many times over.
Timing your claim correctly can significantly affect the tax benefit you receive.
The most tax-efficient approach is to claim capital allowances in the tax year the expenditure is incurred. If you use the Annual Investment Allowance, you can deduct 100% of qualifying expenditure in year one, up to the current AIA limit of £1 million. This can generate a substantial tax refund or reduction in your tax bill in the year of conversion.
If you missed claiming in the original year, you can make retrospective claims by amending prior tax returns (up to four years back for self-assessment). For older expenditure, the rules are more complex — your accountant can advise on whether a claim is still possible.
For limited company structures, capital allowances reduce corporation tax profits. The timing flexibility is similar, but the interaction with other reliefs (such as Structures and Buildings Allowance on the non-qualifying element) means early professional advice is important.
If you are purchasing an existing HMO, you can claim capital allowances on the qualifying fixtures already in the property — but only if the seller has not already pooled them. A Section 198 election between buyer and seller is required to transfer the allowances.
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Yes. Capital allowances on furnished residential lettings are available to individual landlords, not just companies. The allowances reduce your taxable rental income. However, if you let unfurnished, you may instead claim Replacement of Domestic Items Relief for furniture and appliances. Your accountant can advise which route saves more tax.
Most HMO capital allowances surveys cost between £1,500 and £3,000, depending on the project size and complexity. Some firms charge a percentage of the tax saving identified instead of a fixed fee. The surveyor fee is itself tax-deductible as a professional fee. On a typical HMO conversion, the additional tax saving from a professional survey far exceeds the survey cost.
Yes. You can amend self-assessment returns up to four years after the filing deadline. For older expenditure, the position is more complex but claims may still be possible through your accountant. There is no time limit on making a first capital allowances claim for a property — but the relief may need to go into the writing-down pool rather than being claimed under AIA.
Capital allowances cover plant, machinery, fixtures, and integral features (claimed at 18% or 8% per year, or 100% under AIA). The Structures and Buildings Allowance (SBA) covers the structural element of a building at 3% per year over 33 years. For an HMO conversion, you may be able to claim both — capital allowances on qualifying fixtures and SBA on the structural works.
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