What happens if landlords do not declare rental income?

If you leave rent off your tax return, HMRC can collect the tax, interest and a penalty for up to 20 years back. In October 2026, telling HMRC first through the Let Property Campaign usually means a lower penalty.

Undeclared rent does not go away. HMRC can still assess the tax, it charges interest from the date the tax was due, and it can add a penalty. How much you pay depends mostly on why the rent was missed and whether you told HMRC before it asked.

When you don't need to tell HMRC

The property allowance covers up to £1,000 a year of income from property. GOV.UK says that if your gross property income is £1,000 or less, you will not need to tell HMRC, unless you cannot use the allowance. Above £1,000 and up to £2,500, you contact HMRC. Above £2,500 after allowable expenses, or £10,000 before them, you report it on a Self Assessment tax return. The allowance does not apply to tax years before 2017 to 2018.

You cannot use the allowance in a tax year if any of your property income comes from a company you or someone connected to you owns or controls, a partnership where you or someone connected to you is a partner, or your employer or your spouse's or civil partner's employer. You also cannot use it if you claim the tax reducer for finance costs such as mortgage interest on a residential property. In those cases, £1,000 or less of rent can still need to be declared.

How far back HMRC can go

The Taxes Management Act 1970 sets the time limits, and the Let Property Campaign guide uses the same ones. The penalty ranges in the table are for rent from UK property.

Penalties are a percentage of what HMRC calls potential lost revenue. In our reading, a landlord who never registered for Self Assessment is looked at under the failure to notify rules, and one who sent a return but left the rent off is looked at under the inaccuracy rules. The 4 year line is the ordinary time limit in the Act.

Rent from property abroad is different. The campaign guide says HMRC can charge penalties of up to 100% of the tax if the income arose in the UK, but up to 200% for an offshore liability, so the maximums in the table do not apply to overseas rent.

What this means for you

Say you let a flat from May 2021 and never registered. In our reading, that is a failure to notify, so HMRC can go back to the 2021-22 tax year. In our reading of the campaign guide, telling HMRC in October 2026 means 2021-22 to 2024-25 go in a Let Property Campaign disclosure, while 2025-26 and 2026-27 go on Self Assessment tax returns. If you tell HMRC yourself and it was not deliberate, the penalty range is the lower unprompted one. If you have a reasonable excuse for a failure that was not deliberate, and told HMRC without unreasonable delay once it ended, HMRC says it will not charge a penalty.

Interest runs on top. GOV.UK says late payment interest is set at the Bank of England base rate plus 4% from 6 April 2025, and lists 7.75% from 9 January 2026.

HMRC says it may get information about you from others. It also says that in exceptional circumstances an incomplete disclosure may be considered under HMRC Criminal Investigation Policy, and in such cases the material in the disclosure could be used as evidence.

If you are letting now and have not registered yet, start with how to tell HMRC you are a landlord and how to register for Self Assessment as a landlord.

Steps to put it right

1. Work out which tax years you had rent in, using your share if you own the property jointly.
2. For each year, check whether you can use the £1,000 allowance, then check your gross rent against it and the £10,000 limit, then take off allowable expenses and check the profit against the £2,500 limit.
3. Put rent from the current tax year and the year before on a Self Assessment tax return, not in a disclosure. If you are not registered for Self Assessment, register now. If HMRC sent you a return for any year from 2022-23 onwards that is still outstanding, complete it and leave that year out of the disclosure.
4. For the earlier years, tell HMRC you intend to make a disclosure through the Let Property Campaign on GOV.UK. HMRC gives you a disclosure reference number and a payment reference number, and sends a notification acknowledgement.
5. Within 90 days of receiving that acknowledgement, make your disclosure and pay what you owe, including interest and any penalty. If you cannot pay it all, speak to HMRC first.
6. Keep records of rent and costs from now on. Rent also counts towards Making Tax Digital, and the free MTD check shows whether you are affected.

If you cannot pay in one go

The campaign guide says HMRC expects payment with your disclosure. If you cannot pay in full, call the Let Property Campaign Helpline as soon as possible, and do not send your disclosure or payment until you have spoken to HMRC. Have ready your disclosure reference number, payment plan, income and outgoings, and what you own and owe.

If you cannot pay by the date on your notification acknowledgement, agree payment arrangements with HMRC by then. Otherwise, the guide says, you cannot disclose under the campaign or get the certainty of its terms.

HMRC charges interest from the date tax is due until it is paid, so paying sooner keeps the interest down. Our guide to Self Assessment late payment penalties and interest covers how the charges build up. The landlord section has the rest of our landlord guides.