Landlord Self Assessment: prepare the portfolio records before the deadline

Prepare your 2025/26 rental records for Self Assessment. Check October and January deadlines, late-filing penalties and the separate MTD regime.

With several properties to look after, preparing your tax records can feel like another job on an already busy list. Start with the two dates that matter most for the 2025/26 tax year: HMRC must receive a paper return by 31 October 2026, and an online return by 31 January 2027. [1] The rest of this guide sets out the records worth gathering, so the filing window is not the first time you look at a year's paperwork.

For the 2025/26 tax year, the standard Self Assessment deadlines are 31 October 2026 for paper returns and 31 January 2027 for online returns. Payment is normally due by 31 January 2027. Portfolio landlords should plan the records review separately from submission: filing a return and paying the bill are distinct obligations. [1]

Quick answers on the deadlines

Paper return: HMRC must receive it by 11:59pm on 31 October 2026. [1]
Online return: submit it by 11:59pm on 31 January 2027. [1]
Payment: pay what you owe by 11:59pm on 31 January 2027. [1]
Paying through your tax code: the online return must reach HMRC by 11:59pm on 30 December 2026. [1]
Registered after 5 October 2026: HMRC writes with a different filing deadline, three months from the date on the letter or email, but payment still falls due by 11:59pm on 31 January 2027. [1]

Confirm which deadlines apply

The tax year covered here ran from 6 April 2025 to 5 April 2026. HMRC publishes these standard dates:

31 October 2026: HMRC must receive paper returns.
30 December 2026: online filing deadline if requesting collection through a PAYE tax code, where eligible.
31 January 2027: online filing and the normal tax payment deadline.
31 July: a further payment date where payments on account apply. [1]

The notification deadline is 5 October 2026 where a person needs to tell HMRC they must complete a return under the conditions in its guidance. Not every new landlord automatically has the same filing obligation. If the deadline has passed before you act, check HMRC’s instructions promptly: a later deadline for submitting the return does not automatically move the payment deadline. [1]

Understand the late-filing exposure

For the standard Self Assessment regime described by HMRC, late filing starts with a £100 penalty. After three months, daily £10 penalties can apply up to £900. At six months, a further 5% of tax due or £300 applies, whichever is greater; at twelve months, another such charge applies. [2]

Late payment has separate penalties and interest. Do not treat submitting the return as settling the bill. [2]

These are not universal rules for every current reporting obligation. HMRC publishes a separate penalty regime for Making Tax Digital for Income Tax. If you are within MTD, review that guidance for the relevant period rather than applying this ladder to quarterly updates. [3]

Gather the records GOV.UK lists for rental income

HMRC's guidance on keeping your pay and tax records says you should keep details of: [4]

the dates when you let out your property
all rent you get
any income from services you give to tenants, for example if you charge for maintenance or repairs
rent books, receipts, invoices and bank statements
allowable expenses you pay to run your property, for example services you pay for such as cleaning or gardening

The same guidance notes there are rules about what you can and cannot claim as expenses on your tax return. [4]

Working property by property, a simple way to check nothing is missing is to list, for each one: the letting dates, the rent received, any charges to tenants for services, the receipts and bank statements behind those figures, and the expenses claimed. Where a line is blank or a receipt cannot be found, add it to a questions list for your accountant before the filing window closes, rather than guessing how it should be treated. This is an organising suggestion, not an HMRC requirement.

Build a review file for each owner and business

A practical preparation checklist is to:

1. Reconcile recorded rent with receipts and investigate differences. 2. Match expenses to supporting invoices and the relevant property. 3. Separate repairs, improvements and domestic-item replacements for review. 4. Retain finance statements and distinguish interest from loan repayments. 5. Confirm the ownership and income-allocation position. 6. Send unresolved questions to your accountant before the filing window closes.

These are workflow suggestions, not substitutes for HMRC’s rules on taxable income or deductible costs.

Use the late-filing penalty calculator for an estimate under the regime it describes. It does not cover every penalty scenario or replace an HMRC notice.

LetSentry helps organise property income, expenses and receipts. It is a record-keeping tool, not HMRC-recognised MTD software, and does not submit tax returns. Explore LetSentry’s buy-to-let portfolio tools alongside your existing accountant or filing arrangements.

Official sources

1. GOV.UK: Self Assessment deadlines 2. GOV.UK: Self Assessment penalties 3. GOV.UK: penalties for Making Tax Digital for Income Tax 4. GOV.UK: Keeping your pay and tax records — Rental income

General information, not individual tax advice. Check your HMRC notices and the rules for your reporting period.

Last reviewed against official sources: 26 October 2026.

Sources: - GOV.UK: Self Assessment deadlines (accessed 2026-09-21): https://www.gov.uk/self-assessment-tax-returns/deadlines - GOV.UK: Self Assessment penalties (accessed 2026-09-21): https://www.gov.uk/self-assessment-tax-returns/penalties - GOV.UK: penalties for Making Tax Digital for Income Tax (accessed 2026-09-21): https://www.gov.uk/guidance/penalties-for-making-tax-digital-for-income-tax - Finance Act 2009, Schedule 55: penalties for failure to make returns (accessed 2026-09-21): https://www.legislation.gov.uk/ukpga/2009/10/schedule/55 - GOV.UK: Keeping your pay and tax records: Rental income (accessed 2026-10-25): https://www.gov.uk/keeping-your-pay-tax-records/rental-income

Published: 2026-09-21.

Last reviewed: 2026-10-26.

General summary; not legal advice.