Rental Income Tax UK: What Landlords Owe HMRC, How It Is Calculated and What Happens If You Do Not Declare It

How Rental Income Is Taxed in the UK

Rental income from UK property is taxed as property income under Part 3 of the Income Tax (Trading and Other Income) Act 2005. It is added to other income sources (employment income, pension income, self-employment income) to determine the taxpayer's total income, and taxed at their marginal rate: 20% basic rate, 40% higher rate, or 45% additional rate depending on total income. Scottish taxpayers pay the rates set by the Scottish Government, which differ from UK rates above the basic-rate band.

The taxable rental profit is calculated as gross rental income minus allowable expenses for the tax year. The tax year runs from 6 April to 5 April. Rental income must be declared on a self-assessment tax return. Landlords who have not previously filed self-assessment returns are required to register with HMRC by 5 October following the end of the first tax year in which they receive rental income. HMRC's online service at gov.uk/register-for-self-assessment handles the registration process.

HMRC data published in 2025 shows approximately 2.8 million taxpayers declare rental income through self-assessment. The Office for National Statistics estimates that the private rented sector covers approximately 4.6 million households in England alone. The discrepancy suggests material levels of undeclared rental income across the UK, which HMRC addresses through its Let Property Campaign and data matching programmes.

The £1,000 Property Income Allowance

The property income allowance, introduced by the Finance Act 2017, allows individuals with gross property income below £1,000 per year to receive that income tax-free without filing a self-assessment return for the property income. For landlords with gross rental income between £1,000 and £2,500 per year, the allowance can be claimed as an alternative to deducting actual expenses - the landlord pays tax only on income above £1,000 rather than calculating profit after allowable expenses.

For most landlords with meaningful rental income, the allowable expenses approach produces a lower tax bill than the £1,000 allowance, and the allowance is most relevant for small-scale property letting including room rental, informal arrangements, and short-term holiday letting with low expenses.

Allowable Expenses for Rental Income

Allowable expenses that can be deducted from gross rental income to calculate taxable profit are defined by HMRC's Property Income manual (PIM). The main categories of allowable expense are: letting agent fees and management charges; repair and maintenance costs for the property (but not capital improvements, which are not allowable as revenue expenses); buildings and contents insurance premiums for the rental property; accountancy and professional fees directly related to the rental property; ground rent and service charges for leasehold properties; council tax, water rates, and other utility bills paid by the landlord (not by the tenant); and advertising costs for finding tenants.

Capital expenditure - work that improves the property beyond its original condition rather than maintaining it - is not deductible as a revenue expense. Replacing a kitchen with a similar standard kitchen is maintenance (deductible); replacing a standard kitchen with a luxury kitchen is improvement (not deductible). The distinction can be complex in practice and is an area where HMRC frequently challenges landlord expense claims.

Mortgage Interest Relief: The Section 24 Rules

Section 24 of the Finance Act 2015 fundamentally changed how mortgage interest is treated for individual landlords. Prior to April 2020, landlords could deduct mortgage interest in full from rental income to calculate taxable profit. From April 2020 onwards, individual landlords (not companies) can no longer deduct mortgage interest as an expense. Instead, they receive a 20% tax credit equal to 20% of the mortgage interest paid.

The practical consequence is that higher-rate taxpayer landlords are significantly worse off under Section 24 than under the previous rules. Under the old system, a higher-rate taxpayer with £10,000 of rental income and £8,000 of mortgage interest paid tax on £2,000 profit at 40%, resulting in a £800 tax bill. Under Section 24, they pay tax on £10,000 of income at 40% (£4,000) minus a 20% tax credit on £8,000 of mortgage interest (£1,600), resulting in a £2,400 tax bill - three times higher. This structural change has significantly reduced the profitability of leveraged buy-to-let investment for higher-rate taxpayers.

The Section 24 restriction applies to individual landlords and partnerships. Properties held through a limited company continue to deduct mortgage interest as a business expense in full, which is why many landlords have incorporated their property portfolios since 2017. The decision to incorporate involves Stamp Duty Land Tax on the transfer, Capital Gains Tax potentially crystallising, and the complexity of extracting profits from a company - it is not straightforward and requires professional advice.

How HMRC Identifies Undeclared Rental Income

HMRC's Connect data system matches information from multiple sources to identify individuals who may have undeclared rental income. Data sources include Land Registry property ownership records, letting platform data (HMRC has data sharing agreements with major platforms including Airbnb, Rightmove-connected letting agents, and others), mortgage lender data identifying properties with buy-to-let mortgages, council tax records identifying properties with different owners and occupiers, electoral roll data, and court records including possession proceedings.

The Let Property Campaign, running since 2013, invites landlords with undeclared rental income to disclose voluntarily. Voluntary disclosure through the campaign typically attracts lower penalties than HMRC-initiated investigation. HMRC distinguishes between innocent mistakes, careless non-disclosure, and deliberate concealment. Penalties for careless non-disclosure range from 0% to 30% of the unpaid tax; penalties for deliberate non-disclosure range from 20% to 70%; penalties for deliberate and concealed non-disclosure range from 30% to 100%. Interest on underpaid tax accrues at HMRC's published rate from the date the tax was due.

Frequently Asked Questions

Do I need to declare rental income under £1,000?

No. Gross rental income below £1,000 per year is covered by the property income allowance and does not need to be declared on a self-assessment return. Income between £1,000 and £2,500 must be declared but the £1,000 allowance can be claimed instead of actual expenses. Income above £2,500 must be declared in full on a self-assessment return.

What expenses can I deduct from rental income?

Allowable deductions include letting agent fees, repair and maintenance costs (not capital improvements), buildings and contents insurance, accountancy fees, ground rent and service charges for leasehold properties, and utility bills paid by the landlord. Mortgage interest is not deductible as an expense for individual landlords - instead, a 20% tax credit applies to the interest paid (Section 24 rules since April 2020).

What is the HMRC Let Property Campaign?

The Let Property Campaign is an HMRC voluntary disclosure facility allowing landlords with undeclared rental income to come forward and pay what is owed with typically reduced penalties compared to an HMRC-initiated investigation. Landlords who believe they may have undeclared rental income should use HMRC's Let Property Campaign disclosure facility at gov.uk/guidance/let-property-campaign before HMRC contacts them.

How does HMRC find out about undeclared rental income?

HMRC's Connect data system matches Land Registry ownership records, letting platform data, mortgage lender records, council tax data, and electoral roll information to identify properties being rented that are not generating declared rental income. HMRC also has data sharing arrangements with major letting platforms. Undeclared rental income is one of HMRC's most active compliance areas.