Why it matters
What SA105 (Property Pages) means for a landlord
The SA105 is where the whole year’s letting comes together for tax, income, allowable expenses, the Section 24 mortgage-interest credit, and any losses carried forward. As MTD for Income Tax phases in (£50,000+ income from April 2026, £30,000+ from April 2027, £20,000+ from April 2028), affected landlords keep digital records and file quarterly, then confirm the figures in a year-end declaration. Landlords below the threshold, or filing through an accountant, still use the familiar SA105 route.
Worked example
How it plays out
Anya has two flats and files a Self Assessment return. On the UK property pages she reports £18,000 of rent and £4,200 of allowable expenses, and enters her £5,000 of mortgage interest as residential finance costs, so HMRC applies the basic-rate credit instead of treating it as an expense.
Common mistakes
Where landlords go wrong
- 01Putting mortgage interest in with ordinary expenses.
- 02Leaving out your share of a jointly owned property.
- 03Using holiday let rules for years after April 2025.
What to do
A short checklist
- Keep totals per property through the year.
- Keep finance costs separate from other expenses.
- Check whether Making Tax Digital applies to you.
Sources
Checked against these sources on 16 September 2026. A guide to the rules in England, not legal advice: for a dispute or a possession claim, speak to a solicitor.
