You might think you do not have to pay UK tax on rental income from a UK property if you live overseas or are resident in another country. In practice, UK rental income can still create UK tax and reporting obligations, and it is common for landlords to discover the issue only after several years have passed.
Many landlords only come across the Let Property Campaign once they realise rental income has not been declared correctly in the past. A common concern at that point is how far back the disclosure needs to go. This guide explains how to work out which years should be included under the Let Property Campaign, why the reason for the error matters, and the common mistakes that can lead to problems later.
What the Let Property Campaign is (and who it affects)
The Let Property Campaign is a disclosure facility set up by HMRC for people who have rental income that has not been declared correctly for tax purposes.
It applies where someone:
The campaign is aimed primarily at individual landlords, including:
It can also apply where:
The campaign is not limited to “professional landlords”. HMRC guidance indicates that the campaign is intended to cover anyone with undeclared or underdeclared rental income, regardless of the size of the portfolio or the level of income.
What the Let Property Campaign is designed to do
The purpose of the Let Property Campaign is to give landlords a way to:
Importantly, the campaign does not limit HMRC’s legal powers. HMRC can still:
However, HMRC guidance makes clear that coming forward voluntarily through the campaign is generally treated more favourably than waiting for HMRC to identify the issue through compliance activity.
What the Let Property Campaign is not
It is equally important to understand what the campaign does not do.
The Let Property Campaign:
HMRC expects the disclosure to be complete and accurate, covering all relevant rental income and the tax years where that income has resulted in unpaid tax, within the period determined by the applicable rules.
What landlords are expected to do under the campaign
HMRC’s guidance expects landlords using the Let Property Campaign to:
The key point is that the landlord is expected to take responsibility for deciding which years are included, based on HMRC’s rules. HMRC will then review the disclosure and may ask questions if it believes the period or figures are incorrect.
Why the number of years you must disclose depends on behaviour
When landlords first hear about the Let Property Campaign, many assume HMRC applies a fixed rule, such as “go back six years”. In reality, HMRC does not use a single time limit for everyone.
Instead, HMRC looks at why the rental income was not declared correctly. This is known as the landlord’s behaviour, and it determines how far back HMRC is allowed to assess and, therefore, how many years you must disclose.
When can HMRC use the extended time limits?
The longer “six-year” and “twenty-year” time limits are not automatic. HMRC can only use them where certain conditions are met. In broad terms:
This is why the “behaviour” description matters. It is not just a penalty point. It also affects whether HMRC can lawfully go back beyond the normal time limit.
The three behaviour categories HMRC uses
HMRC groups behaviour into three broad categories. The wording matters, but the idea behind each category is straightforward.
Careless behaviour
Careless behaviour covers situations where rental income was not declared correctly because reasonable care was not taken, but there was no intention to underpay tax.
This can include:
Where the issue arose in this way, the disclosure period usually goes back up to six tax years.
What “reasonable care” means
HMRC guidance explains reasonable care as the behaviour expected of a prudent and reasonable person in the taxpayer’s position. People do make mistakes, and an error does not automatically mean carelessness. Importantly, seeking appropriate help, such as using an accountant or professional adviser, can be strong evidence that reasonable care was taken.
Example
A landlord declares rental income but claims expenses that are not allowable because they misunderstood the rules. They had not deliberately tried to reduce their tax bill. The error is identified several years later. In this type of case, the disclosure would normally go back up to six years.
Deliberate behaviour
Deliberate behaviour applies where rental income was left out knowingly.
This can include situations such as:
Where income was knowingly not declared, HMRC can assess tax going back up to twenty tax years, provided the statutory conditions for extended time limits are met.
Example
A landlord rents out a property for several years and does not register for tax, despite knowing that the income should be declared. When the issue is later addressed, the disclosure may need to go back up to twenty years.
Deliberate and concealed behaviour
This category applies where rental income was not only left out deliberately, but steps were taken to hide it.
This might involve:
As with deliberate behaviour, the disclosure period can extend up to twenty tax years, but penalties are usually higher because of the concealment.
Example
A landlord receives rent into an account not connected to their name and does not keep records of the income. This would fall into the most serious category.
Why this matter for penalties and interest
Behaviour does not only affect how far back HMRC can assess. It also influences penalties. More serious behaviour generally leads to higher penalty ranges. In addition, interest is charged separately on any tax paid late, running from the original due date until payment is made.
This is why correctly identifying and explaining behaviour is so important. It affects:
Why this matters when making a disclosure
The disclosure period must reflect the true nature of what happened. It cannot be shortened simply because records are missing or income was small in earlier years.
Getting this classification right at the outset is important. If the behaviour is described incorrectly, the disclosure may be challenged and the period extended later.
How many years you must disclose in practice
Once the reason for the error has been identified, the next step is to work out which tax years must be included in the disclosure. This is not about choosing a convenient period. It is about applying the correct look-back period and then identifying the years where rental income resulted in unpaid tax.
The disclosure is always made by reference to tax years, not calendar years.
Start with the most recent tax year and check whether a tax return is needed
In many cases, the most recent tax year will be dealt with through the normal Self-Assessment process rather than being treated purely as part of a historic “catch-up” calculation. For example, if the latest year has ended and a tax return is required, HMRC would normally expect that year to be reported in a tax return in the usual way, with the Let Property Campaign used to correct earlier years.
This is particularly relevant where:
Counting back: how far the disclosure can go
From the most recent relevant year, you then look back:
The key point is that you only go back to years where there was letting activity and underpaid tax. If the property was not let in earlier years, or there was no rental income (or other underdeclared income) in those earlier years, those years do not form part of the disclosure.
Example - Careless Behaviour
A landlord realises in 2025 that rental income was not declared correctly because they misunderstood the rules. The behaviour is treated as careless.
In this case, the correction would normally focus on the most recent six tax years where there was unpaid tax on rental income. For instance, that might be:
2019/20
2020/21
2021/22
2022/23
2023/24
2024/25
The landlord should review those years and identify which years actually contain underdeclared rental income that resulted in unpaid tax.
Example - Deliberate Behaviour (and why the start year depends on the facts)
A landlord has been renting out a property since 2010 and knowingly did not declare the income. The issue comes to light in 2025.
Because the behaviour is deliberate, the assessment time limit can extend up to twenty years, but the disclosure does not automatically start twenty years back. It starts from the first year in which there was letting income that led to unpaid tax.
So, if the property started being let in 2010/11 and there was no underdeclared rental income (and no other underdeclared income relevant to the disclosure) before that point, the disclosure would start from 2010/11, not earlier years when the property was not let.
When behaviour changes over time
In some cases, the reason rental income was not declared correctly is not the same throughout the entire period. This is common where a landlord’s understanding of their tax obligations develops over time.
For example, in the earlier years a landlord may genuinely not have realised that rental income needed to be declared, or may have misunderstood the rules. In later years, the landlord may have become aware that tax was due but still chose not to declare the income.
Where behaviour changes in this way, HMRC looks at the most serious behaviour when considering how far back it is allowed to assess. This means that later deliberate behaviour can extend the maximum look-back period, even if the issue began as a careless error. However, the disclosure still only covers years where there was letting activity and unpaid tax.
Example
A landlord starts letting a property in the 2014/15 tax year. From 2014/15 to 2017/18, the rental income is not declared because the landlord did not realise it was taxable. From 2018/19 onwards, the landlord becomes aware that the income should be declared but continues not to do so.
Although the early years involved misunderstanding, the later deliberate behaviour means HMRC may be able to assess up to twenty years. In practice, however, the disclosure would start from 2014/15, because that is when the letting (and any loss of tax) began, not earlier years when the property was not let.
You cannot exclude a year simply because income was low
A common misunderstanding is that earlier years can be ignored because rental income was small. Low income on its own does not mean a year can be excluded if there was tax underpaid for that year.
However, under the Let Property Campaign, the disclosure is focused on years where rental income resulted in unpaid tax. If, after deducting allowable expenses, a year results in a rental loss so that no tax is due, HMRC’s guidance says that year does not need to be included in the disclosure.
The key distinction is between:
Why accuracy matters at this stage
Choosing the correct years is one of the most important parts of the Let Property Campaign process. If taxable years are missed, or behaviour is misclassified, the disclosure may be challenged and extended later. This can lead to additional penalties and interest.
Taking the time to identify the correct years where tax was underpaid, and explaining clearly why earlier years are excluded, helps ensure the disclosure is accurate and brings matters to a proper conclusion.
Including years with no tax to pay or losses
A common area of confusion under the Let Property Campaign is how to treat years where rental income was low, fully covered by allowances, or resulted in a loss.
Under the Let Property Campaign, the disclosure is normally focused on years where rental income resulted in tax being underpaid. If, after deducting allowable expenses, a year results in a rental loss so that no tax is due, HMRC’s guidance says that year does not need to be included in the disclosure figures.
That said, loss years can still be relevant. Rental losses may be carried forward and set against profits in later years. For that reason, landlords should retain the calculations and supporting records for loss years, even though those years are not included in the disclosure itself.
Example
A landlord incurs significant repair costs in the 2020/21 tax year, resulting in a rental loss, followed by taxable rental profits in later years. The 2020/21 loss year does not need to be included in the Let Property Campaign disclosure, but the loss calculations should be kept because they affect how the later profits are worked out.
Where rental income was low but still resulted in tax being underpaid, that year should normally be included in the disclosure. The key distinction is whether a tax liability arose, not simply the level of income.
Getting this distinction right helps avoid unnecessary complications and reduces the risk of the disclosure being challenged.
What to do if records are missing or incomplete
Many landlords worry about making a Let Property Campaign disclosure because records for earlier years are missing or incomplete. This is common, particularly where rental activity started many years ago. Missing records do not remove the requirement to disclose years where tax was underpaid, nor do they reduce HMRC’s ability to assess those years.
Where full records are not available, the expectation is that the landlord makes a reasonable attempt to reconstruct the figures for the relevant years. The aim is not perfection, but a fair and honest estimate based on the information that can still be obtained.
In practice, rental income can often be reconstructed using alternative sources such as bank statements, letting agent records, tenancy agreements, or correspondence showing rental amounts. Expenses can usually be estimated using invoices that are available, historic patterns of costs, or reasonable assumptions based on the nature of the property and the period involved.
Example
A landlord no longer has full records for the early years of a letting, but bank statements show regular rental receipts and mortgage payments. These can be used to estimate rental income and finance costs for those years, even if individual invoices are missing.
It is important to be consistent and realistic when estimating figures. Inflating expenses or understating income because records are incomplete can undermine the credibility of the disclosure. Where assumptions are made, they should be reasonable and capable of explanation if questioned.
If records are genuinely unavailable, this should be clearly explained as part of the disclosure. HMRC guidance recognises that older records may not always exist, but expects landlords to do what they reasonably can to put forward an accurate picture.
The key point is that a disclosure should still be made even where records are imperfect. An honest, well-explained estimate is usually preferable to omitting years or delaying disclosure indefinitely.
Common mistakes landlords make when choosing disclosure years
When using the Let Property Campaign, many problems arise not because landlords refuse to disclose, but because they choose the wrong disclosure period. These mistakes can delay the process and increase the risk of further enquiries.
One common mistake is assuming there is a fixed number of years to disclose, such as six years, regardless of circumstances. As explained earlier, the correct period depends on the reason the rental income was not declared. Applying a standard period without considering behaviour can result in earlier years being missed.
Another frequent error is misunderstanding which years actually need to be disclosed. Under the Let Property Campaign, the disclosure is focused on years where rental income resulted in tax being underpaid.
Years where rental income was low but still led to unpaid tax should normally be included. However, if a year results in a rental loss, so that no tax is due, HMRC’s guidance says that year does not need to be included in the disclosure.
Confusing low income, allowances and loss years can lead either to over-disclosure or to incorrect calculations for the years that do need to be included.
Landlords also sometimes underestimate the seriousness of later behaviour. Where income was initially missed through misunderstanding but later knowingly not declared, the disclosure period can extend further back than expected. Describing the entire period as careless in these cases can lead to the disclosure being challenged.
Missing properties or periods of letting is another common issue. This can happen where:
Finally, some landlords delay disclosure because records are incomplete. As discussed earlier, missing records do not remove the obligation to disclose. Reasonable estimates, clearly explained, are generally expected rather than leaving years out altogether.
Avoiding these mistakes helps ensure the disclosure is complete and reduces the likelihood of follow-up questions or extended enquiries.
Summary
The number of years you need to disclose under the Let Property Campaign depends on why rental income was not declared correctly, not on a fixed time limit. Where errors arose through carelessness, the disclosure period is usually shorter. Where income was knowingly left out, the period can extend much further back.
To make a complete disclosure, landlords need to identify the correct behaviour category and work out which tax years involved unpaid tax on rental income. Those years should be included in the disclosure, even if records are incomplete.
Loss years do not normally need to be included, but the calculations should be retained where they affect later profits. Leaving out taxable years or misclassifying behaviour can lead to delays and further questions.
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