How to register and file your first landlord tax return

If you started letting a property in the 2025 to 2026 tax year and your rental income was more than £2,500, you need to register for Self Assessment by 5 October 2026. Registration takes minutes online and HMRC posts you a Unique Taxpayer Reference, the ten-digit number every return is filed under. Tax depends on your personal circumstances, and this is general information rather than advice.

Who has to register at all

The thresholds are gross rent, meaning the rent before any expenses come off. If your total property income for the year was £1,000 or less, the property allowance covers it in full and you do not have to tell HMRC anything. Between £1,000 and £2,500 you should contact HMRC, who may collect the tax through your tax code instead of a return. Above £2,500 you register for Self Assessment and file.

Miss the 5 October deadline and HMRC can charge failure-to-notify penalties, though these are usually reduced to nothing if you register late but still file and pay on time. Do not rely on that. Register the week you decide you need to.

Expenses or the £1,000 allowance, not both

Once you are filing, you choose between deducting the £1,000 property allowance or deducting your actual expenses. You cannot do both. The allowance suits landlords with almost no costs, perhaps a lodger arrangement or a property the tenant maintains. Most landlords with agent fees, insurance and repairs will beat £1,000 in real expenses easily, so claim the actual figures.

Allowable expenses include letting agent fees, landlord insurance, repairs and maintenance, ground rent and service charges, and accountancy for the rental business. Improvements are different: replacing a broken boiler is a repair, adding an extension is capital and only helps when you sell. Most individual landlords with rental receipts of £150,000 or less use the cash basis by default, which means you record rent when it arrives and expenses when you pay them.

Mortgage interest is the trap. Since the Section 24 rules took full effect, interest is not an expense at all. Your full rental profit is taxed first, then you get a credit worth 20% of the interest, which stings if you pay tax at 40%. We cover the mechanics in our separate article on Section 24.

A worked first return

Say you let from April 2025 at £950 a month, so £11,400 for the year. Agent fees, insurance and repairs come to £2,400, and mortgage interest to £4,800. Your taxable profit is £11,400 minus £2,400, which is £9,000, because the interest does not come off. A basic-rate taxpayer owes 20% of £9,000, which is £1,800, minus a finance-cost credit of 20% of £4,800, which is £960. The bill is £840, due by 31 January 2027. A higher-rate taxpayer on the same numbers owes 40% of £9,000 minus the same £960 credit, which is £2,640.

The filing deadlines sit behind the registration one: paper returns by 31 October 2026, online returns and payment by 31 January 2027. Nearly everyone files online, and the January deadline arrives faster than it looks once Christmas is in the way.

Making Tax Digital is now live for larger landlords

Since 6 April 2026, landlords with qualifying income over £50,000 must keep digital records and send quarterly updates to HMRC through compatible software. Qualifying income is your gross rent plus any self-employment turnover, before expenses, taken from your 2024 to 2025 return. The threshold drops to £30,000 in April 2027 and £20,000 in April 2028, both confirmed and in the same guidance.

A first-year landlord is not caught yet, because mandation only bites once a filed return shows qualifying income over the threshold. The return you file this January is the one that decides. If your gross rent plus sole-trader turnover will land over £30,000, choose software that handles quarterly updates now rather than switching systems in a year.

Keep every invoice and statement from day one, because reconstructing a year of expenses each January is how deductions get forgotten and bills get overpaid. And if you are still adding to the portfolio, compare conveyancing quotes for your next purchase in a couple of minutes.