One of the first questions we hear from landlords who discover they may have undeclared rental income is:

“How many years do I need to disclose to HMRC?”

Unfortunately, there isn’t a one-size-fits-all answer. Under HMRC’s Let Property Campaign, the number of years you need to include in a disclosure depends on the circumstances surrounding the error and how HMRC views your behaviour. HMRC’s guidance allows disclosures going back 4, 6 or even 20 years depending on the facts of the case.

 What Is the Let Property Campaign?

HMRC’s Let Property Campaign is for individual landlords who have undeclared rental income from UK or overseas residential properties. Whether you’ve rented out a single property, multiple homes, or even a room in your main residence, you may need to disclose unpaid tax.

You’ll have 90 days to calculate and pay what you owe once you notify HMRC of your intention to disclose. Acting now can significantly reduce penalties and avoid the risk of criminal prosecution

The 4-Year Rule

HMRC can normally assess the previous four tax years if a mistake occurred despite the taxpayer taking reasonable care.

This may apply where:

• You registered for Self Assessment when required.
• You maintained reasonable records.
• A genuine mistake or misunderstanding resulted in the underpayment.

In these situations, HMRC accepts that you attempted to comply with your tax obligations and therefore limits how far back they can assess.

The 6-Year Rule

If HMRC believes the issue arose because of carelessness, they can usually go back six tax years.

Examples could include:

• Not checking whether rental income needed to be reported.
• Failing to keep adequate records.
• Missing information that a reasonable person should have identified.

Many landlords fall into this category. They are not deliberately avoiding tax but may not have taken sufficient care to ensure their tax affairs were correct.

The 20-Year Rule

This is the area that often surprises landlords.

HMRC can potentially look back up to 20 years where there has been:

• A failure to notify HMRC of a tax liability.
• Deliberate behaviour.
• Deliberate omission of rental income.

For example, if someone started renting out a property several years ago and never registered for Self Assessment or informed HMRC about the rental income, HMRC may require a disclosure covering a much longer period.

Common Situations We See

At Premier Tax Solutions, many landlords come to us after receiving an HMRC “nudge” letter or after realising that rental income should have been declared years ago. Typical scenarios include:

• Inheriting a property and renting it out.
• Moving in with a partner and letting out a former home.
• Assuming there was nothing to report because the mortgage payments were higher than the rent received (This is very common!)

In most cases, these are genuine misunderstandings rather than deliberate attempts to avoid tax. However, each situation needs careful review to determine the correct disclosure period and penalty position.

Why It’s Important to Get It Right

We often see people assume they only need to disclose the last few years of rental income.
If too few years are included, HMRC may reject the disclosure or ask for additional information. Conversely, disclosing more years than necessary could result in paying more tax than required.

Before submitting a Let Property Campaign disclosure, it is important to establish:

• When the property was first let.
• Whether HMRC was notified.
• What records are available.
• The reasons the income was not declared.
• Whether HMRC is likely to view the behaviour as reasonable, careless or deliberate.

This assessment will determine how far back the disclosure should go.

The Let Property Campaign offers landlords an opportunity to get their tax affairs up to date before HMRC begins an investigation. HMRC actively encourages landlords with undeclared rental income to come forward voluntarily.

In most cases, making an unprompted disclosure can lead to lower penalties than if HMRC discovers the issue first.

At Premier Tax Solutions, we have extensive experience helping landlords prepare disclosures and negotiate settlements with HMRC.  If you’re unsure how far back you need to go, or you’ve received a letter from HMRC regarding undeclared rental income, we’re here to help.  Book a free discovery call with our team and we’ll help you understand your options and get your tax affairs back on track.