HMRC’s Let Property Campaign Explained – Undeclared Rent, Penalties, Interest and How Far Back HMRC Can Go
By Steve Bicknell FCMA, CGMA
Have you received rental income that you haven’t declared to HMRC?
Perhaps you:
- inherited a property and started letting it;
- became an accidental landlord;
- own a rental property jointly with somebody else;
- assumed your letting agent dealt with the tax;
- thought there was no profit because the rent only covered the mortgage;
- spent substantial amounts repairing or improving the property;
- live abroad but rent out a UK property;
- or simply didn’t realise the income needed to be reported.
If so, ignoring the problem is unlikely to make it disappear.
HMRC operates the Let Property Campaign, which gives many individual residential landlords an opportunity to disclose previously undeclared rental income and bring their tax affairs up to date. HMRC’s current guidance was updated on 6 April 2026.
And there is an important reason to deal with the problem sooner rather than later:
IT CAN BE BETTER TO APPROACH HMRC BEFORE HMRC APPROACHES YOU
HMRC specifically distinguishes between unprompted and prompted disclosures. A disclosure is unprompted where, at the time it is made, you have no reason to believe HMRC has discovered or is about to discover the failure. Otherwise it is prompted.
Let Property Campaign – Quick Answer
If you have undeclared rental income, don’t simply put several years of old rent on your next Self Assessment return and assume the problem is fixed.
The correct route depends on the circumstances, but for many individual residential landlords the process is broadly:
1. Establish what has not been declared
Identify the property, ownership, rental periods and affected tax years.
2. Notify HMRC
Tell HMRC that you intend to make a disclosure.
3. Receive HMRC’s disclosure reference
HMRC provides a Disclosure Reference Number and payment reference.
4. Calculate what is owed
This can include:
TAX + INTEREST + PENALTIES
5. Submit the disclosure
HMRC currently gives you 90 days from its acknowledgement of the notification to submit the disclosure.
6. Pay HMRC
Payment is normally due by the same deadline. If you cannot pay in full, HMRC says you should discuss the position with it before submitting the disclosure.
What Is HMRC’s Let Property Campaign?
The Let Property Campaign has been operating since 2013.
It is aimed at individual landlords who owe tax from letting residential property, including property in the UK and overseas.
It can potentially cover people who:
- rent one residential property;
- own several rental properties;
- rent a room above the Rent a Room threshold;
- have relevant holiday letting income;
- live abroad and rent UK residential property;
- or have inherited a property and subsequently rented it out.
This means the campaign is not just for professional landlords with large portfolios.
Some of the people most likely to get into difficulty are those who never really regarded themselves as landlords in the first place.
The underlying property-sector material also reflects this: examples include inherited property, joint ownership and landlords who misunderstood the effect of mortgage payments or improvements on taxable profit.
Who Cannot Use the Let Property Campaign?
The campaign is primarily for individual residential landlords.
It is not the disclosure route for:
COMPANIES
or:
TRUSTS
and other disclosure routes may be needed for different types of taxpayer or income.
That does not mean undeclared income can simply be ignored. It means the correct HMRC disclosure mechanism needs to be identified.
Common Ways Landlords End Up With Undeclared Rental Income
Not every case begins with somebody deliberately deciding not to pay tax.
The Accidental Landlord
Sarah moves in with her partner but keeps her previous home and rents it out.
She has always been taxed through PAYE and has never normally completed a Self Assessment return.
Three years later she discovers that the rental income should have been considered for tax.
The Inherited Property
John inherits his mother’s house.
Rather than sell it immediately, he rents it out.
He assumes that because the property was inherited and much of the rent is being spent maintaining it, there is nothing to report.
That assumption may be wrong.
Inherited residential property can still generate taxable rental income.
Joint Owners
Two siblings jointly own a rental property.
The rent goes into one bank account and neither has correctly declared their share.
Each individual’s tax position needs to be considered separately.
“The Mortgage Used All the Rent”
David receives £18,000 a year in rent.
His mortgage payments, repairs and other costs come to almost £18,000.
He concludes:
“I haven’t made any money, so there can’t be any tax.”
Unfortunately:
CASH FLOW AND TAXABLE RENTAL PROFIT ARE NOT THE SAME THING
Can HMRC Find Out That I Own a Rental Property?
You should not assume that because HMRC has not contacted you yet, it does not know about the property.
HMRC can compare information it holds with information from other sources.
The more important point is:
DON’T BASE YOUR DECISION TO DISCLOSE ON WHETHER YOU THINK HMRC WILL FIND OUT
If you know there is undeclared rental income, investigate the position.
Waiting for HMRC to contact you may also affect whether the disclosure is treated as prompted or unprompted.
How Far Back Can HMRC Go for Undeclared Rental Income?
This is one of the first questions landlords usually ask.
And the answer is not simply:
“HMRC can always go back 20 years.”
The period depends heavily on what happened and why the tax was underpaid.
Broadly, different time limits can apply depending on whether the taxpayer took reasonable care, was careless, acted deliberately, or failed to notify HMRC of the tax liability.
The practical message is:
THE REASON FOR THE ERROR MATTERS
not just the number of years the property has been rented.
That is why preparing a clear chronology of what happened is so important.
Reasonable Care, Careless or Deliberate?
You should not simply choose whichever description produces the lowest penalty.
The facts need to support the position.
There can be a significant difference between someone who:
- tried to get their affairs right but still made an error;
- failed to take reasonable care;
- or knew tax was due and deliberately failed to report the income.
Those circumstances can affect:
HOW FAR BACK HMRC CAN GO
and:
THE PENALTY POSITION
The underlying disclosure guidance also distinguishes careless, deliberate and deliberate-and-concealed behaviour, with increasingly serious penalty consequences.
Prompted vs Unprompted Disclosure – Why It Matters
This distinction can be very important.
Unprompted Disclosure
HMRC says a disclosure is unprompted where the taxpayer has no reason to believe HMRC has discovered or is about to discover the failure.
Prompted Disclosure
Otherwise the disclosure is prompted.
HMRC expressly says it wants to encourage taxpayers to come forward voluntarily.
So if you already know there is a problem:
DON’T WAIT FOR THE HMRC LETTER SIMPLY BECAUSE IT HASN’T ARRIVED YET
Does an Unprompted Disclosure Mean No Penalty?
Not necessarily.
But the timing and quality of the disclosure can influence the penalty outcome.
HMRC considers matters including:
TELLING
HELPING
GIVING ACCESS
The source material describes these as providing a full explanation, helping HMRC establish the correct liability and providing access to supporting records.
A carefully prepared disclosure is therefore very different from simply sending HMRC a rough estimate.
Worked Example – Five Years of Undeclared Rental Income
Consider a deliberately simplified example.
A landlord discovers that rental income has not been correctly declared for five years.
After reconstructing the records:
| Illustrative amount | |
|---|---|
| Gross rental income | £38,000 |
| Allowable property expenses | (£12,000) |
| Taxable rental profits | £26,000 |
| Estimated additional Income Tax | £7,000 |
| Estimated late-payment interest | £1,400 |
| Illustrative penalties | £1,200 |
| Illustrative total payable | £9,600 |
This is only an illustration.
An actual disclosure should be calculated tax year by tax year, taking account of:
- the landlord’s other income;
- allowances;
- applicable tax rates;
- finance-cost rules;
- losses;
- interest;
- behaviour;
- and the appropriate penalty rules.
The source working example illustrates the same underlying principle: unpaid tax, penalties and late-payment interest are separate components of the eventual liability.
“But My Mortgage Cost More Than the Rent – Surely There Is No Tax?”
This is a very common misunderstanding.
Imagine:
Rent received: £18,000
Mortgage payments: £14,000
Other costs: £3,000
Cash remaining:
£1,000
That does not automatically mean taxable property profit is £1,000.
Mortgage payments may include:
CAPITAL REPAYMENT
and:
INTEREST
Repaying borrowed capital is not an ordinary deductible property expense.
And for individual residential landlords, qualifying finance costs are subject to specific rules rather than being treated like an ordinary expense deduction. HMRC confirms that the full mortgage payment is not deductible and that residential mortgage interest is subject to the finance-cost restriction rules.
Therefore:
CASH PROFIT ≠ TAXABLE RENTAL PROFIT
“I Spent Thousands Renovating the Property – Can’t I Deduct It?”
Again, it depends on the nature of the expenditure.
There is a major distinction between:
REPAIRS
and:
CAPITAL IMPROVEMENTS
HMRC allows qualifying repairs and maintenance as property-business expenses, but improvements and other capital expenditure are not ordinary deductions against rental income.
So do not simply total every builder’s invoice and deduct it from the rent.
What Expenses Can Potentially Be Claimed?
Depending on the year and the circumstances, qualifying expenses can include items such as:
- letting agent fees;
- accountants’ fees;
- buildings and contents insurance;
- repairs and maintenance;
- utilities paid by the landlord;
- service charges;
- ground rent;
- cleaning and gardening;
- and other direct costs of letting the property.
The source checklist similarly identifies agent statements, repairs, insurance, service charges, mortgage-interest information and replacement domestic items as useful disclosure records.
What If I Don’t Have All the Old Records?
This is extremely common, particularly where the problem goes back many years.
But:
MISSING RECORDS DON’T MEAN YOU SHOULD SIMPLY ACCEPT A GUESS
Historic property accounts can often be reconstructed from:
- bank statements;
- letting-agent statements;
- tenancy agreements;
- mortgage statements;
- credit-card statements;
- insurance records;
- invoices;
- service-charge statements;
- council tax records;
- emails;
- deposit information;
- and other evidence.
The source material specifically anticipates reconstructing missing rental history from estimates, emails and tenancy-deposit information where necessary.
And this can make a very substantial difference.
Real Case Study – HMRC Assessment Reduced by £32,085
In one previous case, HMRC contacted a landlord about undeclared property income going back to 2010/11.
HMRC’s original assessment was:
£54,798
We reconstructed the historic records using:
- bank statements;
- letting records;
- expenses;
- credit-card statements;
- and other supporting information.
The work became effectively a forensic reconstruction exercise, with information and questions going backwards and forwards with HMRC over many months.
HMRC ultimately issued a revised assessment of:
£22,713
The reduction was:
£32,085
The case demonstrates an important principle:
DON’T ASSUME HMRC’S FIRST FIGURE IS NECESSARILY THE FINAL ANSWER
The objective is not to invent expenses or artificially reduce the liability.
It is to establish the correct position supported by the best available evidence.
Read the full £32,085 Undeclared Property Income case study
Free Download – Let Property Campaign Checklist
We have prepared a practical checklist to help landlords identify the records and information likely to be needed.
It covers:
- property ownership;
- letting history;
- rent received;
- allowable expenditure;
- mortgage information;
- missing records;
- other taxable income;
- circumstances surrounding the omission;
- and the HMRC disclosure process.
Use this CTA button on the blog:
FREE DOWNLOAD
Let Property Campaign – Landlord Disclosure Checklist
Download the Let Property Campaign Landlord Disclosure Checklist
What Information Should You Gather?
Before calculating a disclosure, I would normally want to establish:
Property
- full address;
- date acquired;
- ownership percentages;
- changes in ownership;
- whether the property has now been sold.
Letting History
- date letting commenced;
- tenancy periods;
- void periods;
- gross rents for each tax year;
- letting-agent statements.
Expenses
- repairs;
- insurance;
- agent fees;
- service charges;
- professional fees;
- replacement items;
- mortgage interest/finance costs;
- other property expenditure.
Wider Tax Position
- employment income;
- self-employment income;
- pensions;
- other property income;
- previous Self Assessment returns;
- losses brought forward.
Explanation
Prepare a chronology explaining:
- when the property was first let;
- what you understood the tax position to be;
- whether advice was obtained;
- why the rent was not declared;
- when the issue was discovered;
- and what happened afterwards.
What If the Property Is Jointly Owned?
Do not automatically report all the rental income on one person’s disclosure.
The ownership and tax treatment need to be established.
This is particularly important for:
- spouses and civil partners;
- siblings;
- unmarried couples;
- unequal ownership;
- and situations where all rent happened to be paid into one person’s bank account.
What If the Property Has Already Been Sold?
Selling the property does not make historic rental income disappear.
There may also be a separate:
CAPITAL GAINS TAX
position to review.
The disposal and the historic rental income should therefore both be considered.
What About Overseas Rental Property?
The Let Property Campaign can potentially cover undisclosed residential rental income from overseas property as well as UK property.
Offshore cases can be more complex because of:
- residence;
- foreign tax;
- double-taxation relief;
- and potentially different penalty rules.
Professional advice is especially sensible where overseas property is involved.
How Is Interest Calculated?
Interest is separate from the penalty.
HMRC charges late-payment interest because the tax was paid later than it should have been.
A multi-year disclosure therefore often requires a separate interest calculation for each affected tax year.
The source working illustrates just how much the interest can build across several historic years.
The 90-Day Let Property Campaign Process
STEP 1 – NOTIFY HMRC
Tell HMRC that you intend to disclose.
↓
STEP 2 – RECEIVE THE DISCLOSURE REFERENCE
HMRC provides the relevant reference numbers.
↓
STEP 3 – RECONSTRUCT THE PROPERTY ACCOUNTS
Calculate the correct result for every relevant year.
↓
STEP 4 – CALCULATE TAX
Take account of other income, allowances, losses and year-specific tax rules.
↓
STEP 5 – CALCULATE INTEREST
Calculate late-payment interest.
↓
STEP 6 – CALCULATE PENALTIES
Consider:
behaviour
prompted vs unprompted
quality of disclosure
↓
STEP 7 – SUBMIT THE DISCLOSURE
Normally within:
90 DAYS
↓
STEP 8 – PAY HMRC
or agree an appropriate payment arrangement.
The source material sets out the same broad sequence: notification, calculation and submission within the 90-day window, followed by payment.
What If I Can’t Afford to Pay HMRC?
Do not let inability to pay immediately stop you from addressing the tax problem.
HMRC has a dedicated Let Property Campaign contact route and advises taxpayers who need help with the campaign to contact it.
The sensible approach is to establish the correct liability and discuss affordability rather than ignoring the disclosure altogether.
Will HMRC Automatically Accept My Disclosure?
No.
HMRC can review the disclosure and request further information.
That is another reason why accurate calculations and supporting evidence matter.
A properly prepared disclosure should be capable of explaining:
- how the figures were calculated;
- what assumptions were made;
- why the omission occurred;
- and what records support the position.
Should I Just Wait and See Whether HMRC Contacts Me?
In my view:
NO
If you have identified undeclared rental income, investigate it now.
Waiting can:
- increase interest;
- leave you dealing with the problem on HMRC’s timetable;
- and potentially turn an unprompted disclosure into a prompted one.
HMRC’s own guidance says it wants to encourage unprompted disclosures.
Let Property Campaign – Decision Tree
Have you received rental income?
NO
→ The Let Property Campaign probably is not relevant.
YES
↓
Was all taxable rental income correctly reported?
YES
→ A historic disclosure may not be needed.
NO / NOT SURE
↓
Has HMRC already contacted you about the rent or property?
NO
INVESTIGATE AN UNPROMPTED DISCLOSURE NOW
YES
TAKE ADVICE BEFORE RESPONDING
↓
Establish:
YEARS + RENT + EXPENSES + FINANCE COSTS + OTHER INCOME
↓
Calculate:
TAX + INTEREST + PENALTIES
↓
Submit the appropriate disclosure and make sure current reporting is brought fully up to date.
Frequently Asked Questions
I forgot to declare rental income. What should I do?
Establish the tax years and amounts involved and consider whether HMRC’s Let Property Campaign is the correct disclosure route.
Can HMRC go back 20 years?
Potentially, depending on the circumstances. The reason for the underpayment and whether you failed to notify HMRC are important.
What if the rent only covered my mortgage?
That does not necessarily mean there is no taxable profit. The full mortgage payment is not an allowable rental expense.
What if I spent thousands renovating the property?
Repairs may potentially be deductible. Improvements and other capital expenditure generally are not ordinary deductions against rental income.
What if I have no records?
Historic accounts can often be reconstructed using bank statements, letting-agent statements, mortgage records and other available evidence.
What if HMRC’s estimate looks too high?
Check it carefully. Our previous property case resulted in a £54,798 HMRC assessment being reduced to £22,713 after the historic records were reconstructed.
Can my accountant make the disclosure?
Yes, an agent can assist with the disclosure process.
Can a limited company use the Let Property Campaign?
The campaign is aimed at individual landlords; other disclosure routes are used for companies.
What if HMRC has already written to me?
Do not ignore the letter. The prompted/unprompted position and the correct response need to be considered carefully.
How long do I get to complete the disclosure?
HMRC currently gives 90 days from acknowledgement of notification.
How Bicknell Business Advisers Can Help
A Let Property Campaign disclosure involves much more than adding up rent received.
We can help:
1. Establish the history
Identify the properties, ownership, letting dates and years affected.
2. Reconstruct the rental accounts
Using bank statements, letting records, mortgage statements, credit cards and other available evidence.
3. Identify allowable expenses
Including repairs versus improvements and the correct treatment of finance costs.
4. Calculate each tax year
Taking account of other income, allowances, tax rates and losses.
5. Calculate interest and penalties
Including consideration of behaviour and whether the disclosure is prompted or unprompted.
6. Prepare the explanation
Set out what happened and why.
7. Deal with HMRC
Assist with notification, submission and queries.
8. Get the current position right
Make sure ongoing rental income is correctly reported going forward.
Don’t Wait for HMRC to Find the Problem
Discovering that several years of rental income have not been declared can be worrying.
But the sensible response is to establish:
WHAT SHOULD HAVE BEEN DECLARED
then:
HOW MANY YEARS NEED CORRECTING
then:
WHAT TAX, INTEREST AND PENALTIES ARE ACTUALLY DUE
And as our £32,085 case study demonstrates, properly reconstructing the records can make a very significant difference.
The objective is not to produce the lowest possible figure.
It is to produce the:
CORRECT, EVIDENCED FIGURE
and make a complete disclosure.
If you have undeclared rental income, inherited a property that has been let, received an HMRC letter or are simply unsure whether historic rental income was correctly reported, Bicknell Business Advisers can review the position and help you decide the appropriate next step.
Useful Blogs
About the Author
Steve Bicknell FCMA, CGMA is Managing Director of Bicknell Business Advisers Limited, specialising in property taxation, landlord tax planning, SDLT, Capital Gains Tax and property company structures throughout the UK.
