Let Property Campaign: How to Declare Undisclosed Rental Income (2026)
Last updated 23 June 2026 · 11 min read · By the LandlordTaxAi Editorial Team
The short answer
If you have not declared all your rental income, HMRC’s Let Property Campaign lets you come forward voluntarily on the best terms. You notify HMRC, receive a Disclosure Reference Number, then have 90 days to work out and pay the tax, interest and a reduced penalty. Coming forward before HMRC contacts you is almost always far cheaper than waiting.
Plenty of landlords end up here by accident — an inherited flat, a room let out for years, a property kept after moving in with a partner — and then realise the rent should have been declared. The good news is that HMRC wants you to put it right, and the Let Property Campaign is the route designed for exactly this. This guide explains how it works, what it costs, and why doing nothing is the worst option. Once you are up to date, keeping compliant digital records stops it happening again.
Who the campaign is for
The Let Property Campaign is open to individual residential landlords who owe tax on rental income they have not declared. That includes accidental landlords, people letting a former home, those renting out a single room above the rent-a-room limit, landlords with multiple properties, and people letting while living abroad. It does not cover companies or commercial property — those have different routes.
The disclosure process, step by step
- 1
Notify HMRC that you want to disclose
Tell HMRC you intend to make a disclosure under the Let Property Campaign, using the Digital Disclosure Service. This starts the clock and records that you came forward voluntarily.
- 2
Receive your Disclosure Reference Number
HMRC sends you a unique Disclosure Reference Number (DRN) and a Payment Reference Number. From the date you notify, you have 90 days to complete everything.
- 3
Work out the tax, interest and penalty owed
Calculate the undeclared rental profit for each year, the tax due, interest for late payment, and the penalty based on why the income was not declared.
- 4
Submit your disclosure and pay
Make a formal disclosure of the figures and pay what you owe within the 90-day window, or arrange a payment plan with HMRC if you cannot pay in full.
The 90-day clock: the countdown starts when you notify, not when you finish. Notify only when you are ready to gather your figures, because you then have just 90 days to calculate and pay everything.
Free calculator · no sign-up
Rental profit & tax calculator
Estimate the tax on your rental income for 2026/27
Result
- Taxable profit (rent − expenses)
- £11,200
- Income Tax at 40%
- £4,480
- Less mortgage interest credit (20%)
- − £1,000
- Tax due on this property
- £3,480
- Income after tax
- £7,720
Estimate based on verified 2026/27 UK rates. Informational only — not personal tax advice.
Reconstruct your rental figures fast
LandlordTaxAi reads years of bank statements and rebuilds your rental income and expenses — exactly what you need for a disclosure.
See how it worksHow far back you have to go
The number of years you must disclose depends on why the income went unreported:
| Behaviour | Years HMRC can go back |
|---|---|
| Reasonable care taken (genuine mistake) | Up to 4 years |
| Careless | Up to 6 years |
| Deliberate | Up to 20 years |
Why coming forward beats waiting
HMRC now cross-references data from letting agents, tenancy deposit schemes, the Land Registry, mortgage lenders and even online listings. The chances of undeclared lettings staying hidden are falling every year. A voluntary, unprompted disclosure attracts the lowest penalties; being contacted by HMRC first means higher penalties and, in serious deliberate cases, the risk of prosecution. If you know there is a gap, the cheapest day to fix it is today.
Frequently asked questions
What is the Let Property Campaign?
It is an HMRC campaign that lets residential landlords who have not declared all their rental income come forward voluntarily and bring their tax affairs up to date on the best possible terms. Because you are disclosing before HMRC catches you, the penalties are far lower than if HMRC opens an investigation first. It has no set end date, so it remains open to landlords in 2026.
How does the disclosure process work?
You notify HMRC that you want to take part, usually through the Digital Disclosure Service. HMRC gives you a unique Disclosure Reference Number, and from the date you notify you have 90 days to calculate what you owe — tax, interest and penalty — and pay it. You then submit a formal disclosure of the figures for each year involved.
How much are the penalties?
The penalty depends on why the income was not declared and how you came forward. An unprompted, voluntary disclosure of a genuine mistake attracts a much lower penalty than deliberate concealment uncovered by HMRC. Penalties are charged as a percentage of the unpaid tax, and coming forward voluntarily — rather than waiting to be contacted — is the single biggest factor in keeping them low. You also pay interest on the late tax.
How many years do I have to disclose?
It depends on your behaviour. If the under-declaration was a genuine mistake despite taking reasonable care, HMRC generally looks back up to 4 years; if it was careless, up to 6 years; and if it was deliberate, up to 20 years. Working out the correct number of years is part of preparing your disclosure, so keep records for every year you let the property.
What happens if I don't come forward?
HMRC receives data from letting agents, the Land Registry, deposit schemes and other sources, so undeclared landlords are increasingly identified. If HMRC contacts you first, you lose the favourable Let Property Campaign terms, penalties are higher, and in serious deliberate cases there is a risk of prosecution. Coming forward voluntarily almost always produces a better outcome.
Written and reviewed by the LandlordTaxAi Editorial Team. Our guides are reviewed against current HMRC guidance and updated when the rules change. Operated by LandlordTaxAi, United Kingdom. Follow us on LinkedIn.
Last reviewed: 23 June 2026 · Based on HMRC guidance on the Let Property Campaign and the Digital Disclosure Service, including the 90-day disclosure window and the look-back periods for reasonable care, careless and deliberate behaviour. This article is informational only and does not constitute tax advice. For larger or deliberate disclosures, take advice from a qualified adviser before you notify HMRC.