The short answer
Replacing old single-glazed windows with double glazing is accepted as a repair, because double glazing is the modern equivalent of the old windows. Claim it 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 |
|---|---|
| Replacing worn single-glazed windows with standard double glazing | Adding new windows where there were none |
| Replacing failed double-glazed units | Upgrades well beyond the original, such as a conservatory or bi-fold doors replacing a wall |
| Window repairs and new locks |
Worked example
New double-glazed windows to replace rotten single-glazed frames cost £4,500. They're the modern equivalent of what was there, so the whole cost is a repair.
| Your tax band | Saving 2026/27 | Saving 2027/28 |
|---|---|---|
| Basic rate | £900 | £1,080 |
| Higher rate | £1,800 | £1,980 |
| Additional rate | £2,025 | £2,205 |
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 25 (property repairs and maintenance). 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
Are new windows in a rental property tax deductible?
Yes, if they replace existing windows. New windows where none existed are capital.
Does it matter that double glazing improves the EPC?
No. An improvement that comes only from using modern materials doesn't make a like-for-like replacement capital.
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.