Received a letter from HMRC about your rental income, a missed CGT deadline, short-term letting, or ATED? This guide explains exactly what HMRC is looking for, why you received it, and — most importantly — what to do next. Part of our free property and land tax guidance hub.
HMRC sends nudge letters when its data systems flag a potential discrepancy. You get one chance to self-correct. Here's how the system works.
HMRC's Connect system is a sophisticated data-matching engine that pulls together information from multiple sources simultaneously. For property owners and landlords, this includes:
When Connect identifies a mismatch — for example, you're registered as a landlord holding a deposit but you have no property income pages on your Self Assessment return — HMRC sends a nudge letter prompting you to check your position.
Do not sign and return a Certificate of Tax Position until you have fully verified your records against your actual bank statements, receipts, and income sources. Signing an inaccurate certificate can be treated as a deliberate act — triggering the highest penalty bands. A nudge letter gives you a chance to self-correct. Use it correctly.
What it is: A targeted letter prompting individual landlords who are registered for Self Assessment but whom HMRC suspects have underreported or entirely failed to declare ongoing residential rental income.
What triggered it: Data integration between HMRC's Connect system, the three statutory Tenancy Deposit Schemes, mortgage lender records, and electoral registers. HMRC has found a mismatch — you appear to be a landlord, but your tax return has no supplementary property pages (SA105).
What HMRC is looking for: Missing rental yields across one or more tax years. If you've rented out a property but not declared the income — even partially, or even for just one year — this letter is designed to find you.
Per HMRC's published guidance, taxpayers who voluntarily disclose through the Let Property Campaign before HMRC opens a formal enquiry typically face significantly lower penalties — in genuine cases of careless (not deliberate) error, penalty rates can be as low as 0%. Formal enquiries can attract penalties of 30%–100% of the unpaid tax.
What it is: A high-volume campaign targeting casual and commercial hosts renting properties on digital platforms.
What triggered it: Since January 2025, UK Digital Platform Reporting Rules legally require third-party platforms (Airbnb, Booking.com, Vrbo, and others) to report host earnings data directly to HMRC. HMRC is now cross-referencing platform data against Self Assessment returns at scale.
What HMRC is looking for: Gross platform income exceeding the £1,000 property allowance that has not been declared. HMRC is also catching hosts who believe they qualify for the Rent-a-Room Scheme — which offers up to £7,500 tax-free — but who do not actually meet the qualifying conditions, which require you to live in the property alongside the guest.
Per HMRC's published guidance, the Rent-a-Room Scheme only applies when you are letting a furnished room in your main home and you continue to live there. If you let the entire property — even briefly — while you are elsewhere, the scheme does not apply and all income above £1,000 is taxable.
What it is: Automated nudge letters targeting individuals who used estimated or rounded numbers on their Self Assessment returns but never submitted final amended figures.
What triggered it: An automated crawl of historical property business schedules, flagging returns where expenses or revenues end in "00" or "50", or where the "provisional figures" box was ticked without a subsequent amendment.
What HMRC is looking for: Landlords who filed placeholder numbers to meet the 31 January deadline but never returned to replace them with finalised, accurate figures.
What it is: Letters targeting individuals who sold a UK residential property but failed to file a Capital Gains Tax return or pay the tax within the 60-day legal window.
What triggered it: Real-time data sharing between HMRC and HM Land Registry. When a property title transfers, HMRC is notified automatically — and flags any disposal where no CGT return has been received within 60 days of completion.
What HMRC is looking for: Sales of second homes, buy-to-let properties, and inherited homes where CGT was due but the standalone online return was not filed and tax not paid within the 60-day window. This applies to UK residents only — non-residents have different rules.
What it is: Letters targeting UK residents with overseas rental properties, or expats living abroad who collect rental income from UK properties.
What triggered it: Data received via the Common Reporting Standard (CRS) — where international banks share account activity with HMRC — alongside UK letting agent annual returns (Form CRL1).
What HMRC is looking for: Two distinct problems: (1) UK tax residents who failed to declare overseas property income on the Foreign section of their return; (2) Overseas expats collecting UK rent without being registered under the Non-Resident Landlord (NRL) Scheme, under which 20% tax must be withheld at source by the letting agent or tenant unless HMRC has granted gross payment approval.
What it is: High-stakes nudge letters addressed to individual directors and shareholders of property investment limited companies.
What triggered it: Algorithmic cross-referencing between the Companies House PSC Register and individual personal Self Assessment accounts. HMRC is specifically looking at companies set up to avoid Section 24 mortgage interest restrictions.
What HMRC is looking for: Landlords who incorporated to bypass Section 24 but then extracted cash from the company to pay personal expenses — without declaring these as dividends or salary. This creates overdrawn director loan accounts, which are liable to Section 455 tax (currently 33.75% on the outstanding loan balance if not repaid within 9 months of the company's accounting year end).
Per HMRC's published guidance, if a director borrows from their own limited company and the loan remains outstanding 9 months after the company's year end, the company pays a temporary tax charge of 33.75% of the outstanding amount. This is repaid to the company when the director repays the loan — but penalties and interest may also apply. Undisclosed overdrawn loan accounts are a primary focus of current HMRC property company campaigns.
What it is: Enforcement letters sent to corporate structures, partnerships, or collective investment schemes that hold high-value UK residential property.
What triggered it: Corporate property registry sweeps mapping entity types against Valuation Office Agency (VOA) pricing data. If a company appears to own a property worth over £500,000 but no ATED return appears in HMRC's records, a letter follows.
What HMRC is looking for: Companies that own a UK residential property valued at more than £500,000 that have failed to file an ATED return — and specifically targeting corporate landlords who qualify for relief but forgot that filing a Relief Declaration Return by 30 April is mandatory even when zero tax is owed.
See our full ATED guide for a complete breakdown of charges, reliefs, and the filing process.
What it is: Micro-targeted prompts challenging the legitimacy of deductions and expenses claimed against rental income.
What triggered it: Postcode-wide anomaly screening within HMRC's Connect database, comparing average repair-to-revenue ratios across regional landlord portfolios. If your claimed expense ratios sit far outside the regional norm, a letter is triggered.
What HMRC is looking for: Landlords who are incorrectly claiming capital expenditure as revenue expenses — for example, claiming the full cost of building a structural extension or carrying out a premium refurbishment directly against rental income, rather than correctly classifying it as a capital improvement (which can reduce Capital Gains Tax on eventual sale, but cannot be deducted from rental income).
What it is: Pre-enquiry warning letters and digital dashboard notifications issued to landlords approaching or crossing the MTD for Income Tax threshold.
What triggered it: HMRC's internal systems have matched landlords' gross rental turnover from filed 2024/25 returns against MTD enrolment registries — and identified those who should now be enrolled but aren't.
What HMRC is looking for: Individuals with total gross property or self-employment income exceeding £50,000 in 2024/25 who have not transitioned to MTD-compatible software and begun quarterly reporting. From April 2026, these landlords are legally required to comply.
Our AI Tax Assistant can help you quickly assess whether MTD applies to your situation — just describe your rental income structure and it will guide you through the thresholds.
A nudge letter is not a formal statutory tax investigation — it is HMRC giving the taxpayer one final opportunity to self-correct on favourable terms.
If you ignore the letter, or return a signed Certificate of Tax Position containing statements you haven't fully verified, HMRC will automatically escalate the file into a hostile, formal tax enquiry. At that point, the best-case penalty rates rise sharply, HMRC takes control of the timeline, and your ability to control the outcome diminishes significantly.
The right response is always the same: verify your records thoroughly, calculate your true position, and use the correct HMRC voluntary disclosure route. If the calculation is complex or there are multiple years involved, matching with a specialist through our expert matching service before you respond is often the smartest first step.
Our guidance explains what to do — but the calculations, the disclosure letter, and any communication with HMRC should involve a professional who has handled exactly this type of compliance check before. Our matching service connects you with a specialist for your specific letter type.
Find my property tax specialist →Answers to the most common questions about HMRC property compliance checks, sourced from HMRC's published guidance.
Use our free guidance to understand your letter type, then match with a specialist who can manage the disclosure process and protect you from further escalation.
Guidance, not advice. This page provides free educational guidance about HMRC property tax compliance checks, based on HMRC's published guidance and publicly available information about HMRC campaigns. UK Tax Hero does not provide formal tax or financial advice, and this guidance does not constitute legal representation. If you have received an HMRC letter, consider engaging a qualified tax professional before responding. Always verify current HMRC guidance at GOV.UK.
