The short answer
The annual gas safety check is a running cost of letting. Claim it in full, normally in box 29 (other allowable expenses) or with repairs in box 25.
It's a revenue cost of running the letting, so it reduces your taxable rental profit at your top rate of tax.
What you can and can't claim
| You can claim | You can't claim |
|---|---|
| Annual gas safety checks (CP12) | Checks on your own home |
| Boiler servicing done at the same visit | |
| Repairs needed to pass the check |
Worked example
A gas safety check costs £90 a year. Over 10 years that's £900 of costs that each reduce taxable profit.
| Your tax band | Saving 2026/27 | Saving 2027/28 |
|---|---|---|
| Basic rate | £18 | £22 |
| Higher rate | £36 | £40 |
| Additional rate | £40 | £44 |
Savings assume the whole amount is taxed at your top rate. Use the landlord tax calculator for your exact figure.
Where it goes on your tax return
On the UK property pages (SA105), enter it in box 29 (other allowable property expenses). Online, it's the matching question in the property section. Our SA105 helper sorts all your costs into the right boxes.
Repair or improvement: how HMRC decides
A repair restores something to its previous condition, even if modern materials make it a bit better. An improvement adds something new or makes it significantly better, and is capital. Timing also matters from 2027: a cost paid before 6 April 2027 saves tax at 20%/40%/45%, after that at 24%/44%/49%. See all landlord expenses A to Z.
Frequently asked questions
Is a landlord gas safety certificate tax deductible?
Yes, in full, every year.
Which box do I use?
HMRC doesn't name one. Most landlords use box 29, or box 25 if done with a repair. Just don't claim it twice.
Sources
- GOV.UK: Work out your rental income when you let property
- HMRC: UK property notes (SA105 Notes 2025)
- HMRC Property Income Manual: repairs, replacements and allowable costs
Sources last checked 10 November 2026. See all our sources and how we keep pages up to date.