This is general information, not tax advice. Tax rules change and individual circumstances vary enormously. Always speak to a qualified accountant about your own situation before filing.
With that said, here is the general shape of what landlords can typically claim on plumbing and heating. Everything below reflects the general position at the time of writing, so check current HMRC guidance or ask your accountant before relying on any of it.
Repairs against improvements
This is the distinction that matters most, and it is where people get caught out.
A repair restores the property to its previous condition, or replaces something like for like. Generally allowable against rental income in the year you incur it.
An improvement makes the property better than it was. Treated as capital expenditure, which affects your capital gains position when you sell rather than your income tax now.
The useful nuance is that replacing an old boiler with a modern equivalent is generally treated as a repair, even though the new one is better, because you are replacing like for like with current technology. You cannot buy a 1990s boiler any more.
Typical examples of work that is usually treated as a repair:
- Fixing a broken boiler
- Repairing a leaking or burst pipe
- Replacing a broken tap with an equivalent one
- Fixing a faulty radiator
- Unblocking drains
- Fixing a roof leak
- Replacing a failed boiler like for like
What you can typically claim
Boiler and heating
- Annual boiler servicing
- Boiler repairs and parts
- Boiler replacement, like for like
- Radiator repairs and valve replacement
- Radiator bleeding carried out as part of a service visit
- Powerflush and system cleaning
- Thermostat replacement, like for like
- Pump repair or replacement
Plumbing
- Leak repairs
- Tap repair or like for like replacement
- Toilet repairs, cistern mechanisms and seals
- Unblocking drains
- Pipe repairs
- Stopcock replacement
- Shower repairs to existing units
- Hot water cylinder repairs
Safety and compliance
- Gas Safety Certificate, annually, which is a legal requirement
- Electrical Installation Condition Report, every five years
- Legionella risk assessment
- Carbon monoxide detector installation, now a legal requirement
- Smoke alarm installation, also a legal requirement
Replacing furniture and appliances
Separate from repairs, there is a specific relief for replacing domestic items in a let property. At the time of writing, the Replacement of Domestic Items Relief, available since April 2016, covers:
- Movable furniture
- Furnishings such as carpets and curtains
- Household appliances
- Kitchenware
The main conditions are that the new item replaces an existing one, it is for the tenant’s sole use, you can only claim the cost of an equivalent item rather than an upgrade, and you must deduct anything you received from selling the old one.
It does not cover fixtures that are part of the building, such as a boiler. Those fall under the ordinary rules for repairs set out above. If you are unsure which side of the line an item falls, check with HMRC or your accountant.
Records to keep
HMRC requires records for at least five years after the relevant submission deadline. For anything that could be capital expenditure, keep it permanently, because you will need it when you sell.
Keep itemised invoices showing the work, date and cost, proof of payment, bank statements showing payments to contractors, before and after photographs for major work, correspondence about work needed, and all gas safety certificates and service records.
Scan everything. Thermal receipts fade to blank within a few years, often before HMRC would ever ask. Cloud storage gives you a safe archive you can reach from anywhere, rather than one that depends on a single filing cabinet or laptop.
Common mistakes
Not keeping receipts. No documentation, no claim. Request an itemised invoice for every job and file it immediately.
Claiming improvements as repairs. HMRC can investigate and penalise this. When it is genuinely borderline, ask your accountant rather than guessing in your favour.
Using cash-in-hand tradespeople. No invoice means no evidence, so you lose the deduction entirely. The apparent saving usually costs you more than it saved.
Forgetting annual compliance costs. Gas safety certificates and EICRs are allowable and routinely get missed at filing time.
Mixing personal and rental expenses. Keep them completely separate, ideally with a dedicated account.
Why a consistent maintenance provider helps
Consistent documentation. The same invoice format every time, easy to file and reference, with a clear audit trail.
Complete service history. If you lose a receipt, your plumber has the record.
Accurate categorisation. A provider who works with landlords regularly understands the repair against improvement distinction and can describe work accurately on the invoice.
Renewal reminders, so you never miss an allowable annual expense simply because nobody prompted you.
We work with landlords and letting agents across the area, and every job comes with a detailed invoice that describes the work clearly, which is what your accountant needs.
The wider financial case for a new boiler
Beyond the tax position, an aging boiler in a rental costs money in ways that are easy to miss.
Insurance. A new boiler with a manufacturer warranty is lower risk, and insurers price that in. Converting from a gravity system to a combi removes the loft tank, which is one of the biggest water damage risks in any property. No loft tank means no tank freezing in a cold snap and no overflow coming through a ceiling. Some insurers offer better terms for properties without one, so it is worth asking yours.
Boiler cover. Many landlords pay £150 to £300 per property per year. A manufacturer warranty of five to ten years often makes that redundant entirely.
Check exactly what the warranty covers before you cancel anything. Many cover parts and labour, but most depend on the boiler being registered and serviced every year. If the warranty does make cover redundant, that saving repeats every year of the boiler’s ten or so year life, on every property, before any insurance difference. If you would rather keep cover, it usually costs less on a new boiler than on an ageing one.
Fewer components. A modern combi has far fewer parts than a gravity system with tanks, a cylinder and separate pumps. Fewer things to fail.
EPC rating. A new efficient boiler improves it, which matters given tightening minimum energy standards for rented property. A better rating can also help the property’s appeal to tenants.
Running costs. Better efficiency means lower energy bills, which matters whichever of you pays them.
Tenants. Reliable heating means fewer breakdowns, fewer emergency call-outs and happier tenants.
Taken together, the annual saving on cover and insurance alone can be substantial across a portfolio, before counting the reduction in emergency call-outs.
Quick reference: generally allowable expenses
At the time of writing, these are generally allowable against rental income:
- Boiler servicing and repairs
- Gas safety certificates
- EICR electrical testing
- Plumbing repairs
- Leak detection and repair
- Drain unblocking
- Powerflush and system cleaning
- Like for like replacements
- Emergency call-outs
- Landlord insurance
- Letting agent fees
- Ground rent and service charges
- Property management fees
- Accountancy fees for your rental accounts
Treat it as a prompt for your records, not a ruling on any particular item.
Get proper advice
Tax rules on landlord expenditure continue to change. Consult an accountant familiar with property taxation, review your position annually, and verify current rules before filing. This page is a starting point for the conversation, not a substitute for it.
Two more things are worth doing. Keep up with changes to HMRC guidance as they are published, and if you have several properties, consider using a property tax specialist. Review your position after any major work too, rather than only at the end of the tax year.
Frequently asked
Is a boiler replacement a repair or an improvement?
Replacing a failed boiler with a modern equivalent is generally treated as a repair and is allowable, because you are restoring the property to its previous condition using current technology. Upgrading to a substantially better system as part of an improvement project is treated differently. This is exactly the sort of question to put to your accountant.
How long do I need to keep records?
HMRC requires at least five years after the relevant submission deadline. For anything that might count as a capital improvement, keep it indefinitely, because it matters when you eventually sell and calculate capital gains.
Can I claim for work I did myself?
You cannot claim for your own labour, only for materials you actually bought and can evidence with receipts. That is one of several reasons using a registered tradesperson who invoices properly usually works out better.
Does the Replacement of Domestic Items Relief cover boilers?
No. At the time of writing, the relief covers movable items such as furniture, furnishings, household appliances and kitchenware. A boiler is part of the building, so replacing one falls under the ordinary rules for repairs instead. Check the current position with HMRC or your accountant.
Can I claim the cost of a gas safety certificate?
Generally yes. At the time of writing, the annual gas safety certificate and the five-yearly electrical inspection are normally allowable against rental income, and they are among the costs landlords most often forget to include. Confirm with your accountant before you file.