The Repair vs. Improvement Line That Costs Landlords £thousands — HMRC's Wholly and Exclusively Test Explained

The HMRC wholly and exclusively test is the single rule that decides whether you can deduct a cost from your rental income. Get it wrong and you lose the deduction, pay more tax, and risk a penalty. The test is simple in theory: the expense must be for your trade, not for you personally. But the practical line between a repair and an improvement is where most landlords slip up.

Revenue expenses are deductible; capital expenditure is not

HMRC divides your spending into two buckets. Revenue expenses are the day-to-day costs of running a property. You can claim them against your rental income in the year you incur them. Capital expenditure is money spent on improving or adding to the asset itself. You cannot claim it as a deduction against rental income. Instead, it sits in the property's cost base and reduces your capital gains tax bill when you sell.

The distinction matters because the sums are large. A like-for-like replacement of a broken boiler is a repair. Replacing that same boiler with a more efficient model that increases the property's value is an improvement. The first is deductible. The second is not.

Air-source heat pumps are capital costs, not repairs

Take the air-source heat pump (ASHP) example. A landlord in Manchester replaces a failed gas boiler with an ASHP to prepare for the 2028 EPC Band C deadline. The boiler was beyond repair. The landlord argues the ASHP is a like-for-like replacement because both provide heat and hot water. HMRC disagrees. The ASHP is a different technology, delivers a different system, and improves the property's energy performance. It is capital expenditure.

This is not a grey area. HMRC's guidance is explicit: the cost of replacing a heating system with a fundamentally different one is capital. The same logic applies to double glazing replacing single glazing, a new roof replacing a leaking one, or adding insulation to an uninsulated wall. Each improves the asset. Each is capital.

What about a like-for-like replacement? If you swap a broken gas boiler for an identical model, that is a repair. If you replace a damaged section of roof with the same tiles, that is a repair. The key question is whether the new item performs the same function as the old one, or whether it does something better.

How the wholly and exclusively test applies to mixed-use costs

The wholly and exclusively test also catches landlords who mix personal and business use. A landlord who uses their rental property's driveway to store their own car cannot claim the full cost of resurfacing that driveway. The expense is not wholly for the trade. The same applies to a phone contract used for both personal calls and tenant management. Only the business portion is deductible.

HMRC expects you to apportion mixed-use costs. If 70% of your phone use is for the rental business, you claim 70% of the bill. If you use a room in the rental property as your own office, you cannot claim the full cost of furnishing that room. The test is strict, and HMRC applies it rigorously.

What this means for your retrofit timeline

This distinction has a direct impact on your compliance planning. The UK's 2028 EPC Band C deadline for rental properties is approaching. Many landlords will need to install insulation, upgrade heating systems, or add solar panels to reach the required rating. These are all capital costs. You cannot claim them against rental income.

But you can plan for them. Capital expenditure reduces your capital gains tax liability when you sell. If you are holding a property long-term, that benefit is real. If you are planning to sell before the 2028 deadline, the capital cost may not help you at all. The buyer will pay the tax on the improved value, not you.

This is why the decision to retrofit is not just a compliance decision. It is a tax decision. A landlord with a 20-year hold period can absorb capital costs more easily than one planning to exit in three years. The same retrofit has different tax consequences depending on your timeline.

Practical steps to stay compliant

Keep separate records for repairs and improvements. When you pay a contractor, ask them to itemise the work. A single invoice that mixes a new boiler (capital) with a service call (revenue) is a problem. You need to split the costs correctly on your tax return.

Take photographs before and after the work. If HMRC challenges your classification, evidence is your defence. A photo of a leaking roof and the same roof repaired is worth more than a written description.

If you are unsure whether a cost is revenue or capital, ask your accountant before you file. The cost of professional advice is itself a deductible revenue expense. The cost of getting the classification wrong is higher: the deduction is denied, interest accrues on the underpaid tax, and penalties can reach 100% of the tax due.

For landlords managing multiple properties, this is not a one-off exercise. Every repair, every upgrade, every replacement needs the same test applied. The wholly and exclusively test is not a box to tick once. It is a discipline that runs through every invoice you pay.

Where to start

Review your last 12 months of property spending. Separate every invoice into revenue and capital. If you have already filed a return that mixed the two, talk to your accountant about amending it. HMRC's rules on voluntary disclosure are more forgiving than their rules on discovered errors.

For new work, agree the classification with your contractor before they start. A written scope of works that states whether the job is a repair or an improvement removes ambiguity at tax time. It also helps your accountant file accurately the first time.

If you are planning a retrofit to meet the 2028 EPC Band C deadline, model the tax impact before you commit. The capital cost may be worth it for the compliance benefit, but it will not reduce your income tax bill. Know that before you sign the contract.

Tracking these costs across a portfolio is exactly the kind of thing Herman handles. See how HermanWa can help you keep compliance and cost records in one place.

— The HermanWa Team