How to File Landlord Self-Assessment in the UK

If you own a rental property in the UK whether it’s a single buy-to-let flat, a house you’ve inherited, or a portfolio of properties you are legally required to report your rental income to HM Revenue & Customs (HMRC). The way to do this is through the Self-Assessment tax return system.

For many landlords, especially first-timers, the idea of filing a Self-Assessment can be daunting. The rules around allowable expenses, property income bands, tax relief, and deadlines can feel overwhelming. However, filing correctly is crucial: it ensures you pay the right tax, avoid penalties, and claim every deduction you’re entitled to.

In this comprehensive guide, we’ll walk you through everything you need to know about landlord Self-Assessment in the UK from registration to submission, allowable expenses, deadlines, and tips to make the process smoother.

Who Needs to File a Landlord Self-Assessment?

You’ll need to file a Self-Assessment tax return if:

• Your rental income (before expenses) is more than £1,000 per tax year. (This is above the property income allowance).
• You want to claim expenses that reduce your rental profit.
• You are a higher or additional rate taxpayer and your rental income pushes you into a higher tax band.
• You receive foreign rental income (e.g., a property abroad).
• You are in a partnership or jointly own property.

Even if your rental profit is small, it’s still worth filing especially if you’re entitled to deductions that could reduce your liability.

HMRC resource: Who must send a Self Assessment tax return

Step 1: Registering for Self-Assessment as a Landlord

If you’ve never filed before, you’ll need to register with HMRC.

1. Create a Government Gateway account (if you don’t already have one).
2. Register online as an individual for Self-Assessment and property income.
3. HMRC will send you a Unique Taxpayer Reference (UTR). Keep this safe it’s your permanent identifier.
4. You’ll also need to activate your online account with a code sent by post.

Important: You must register by 5 October following the end of the tax year in which you started receiving rental income.

Example: If you began renting in June 2024, the tax year ends 5 April 2025. You must register by 5 October 2025.

Register here: HMRC Self-Assessment Registration

Step 2: Record Keeping and Documentation

Good record keeping is the backbone of a smooth landlord Self-Assessment. HMRC can ask to see proof of your claims, and digital tools make compliance much easier.

Keep records of:

• Rental income received (bank statements, rent ledgers).
• Letting agent statements (if applicable).
• Invoices/receipts for allowable expenses (repairs, insurance, etc.).
• Mortgage interest statements.
• Service charge and ground rent bills (for leaseholds).
• Mileage logs if you travel for property management.
• Copies of tenancy agreements.

HMRC recommends keeping records for at least 6 years after the filing deadline.

Helpful resource: HMRC Record Keeping Guidance

Step 3: Understanding Allowable Expenses for Landlords

To reduce your taxable rental profit, you can claim allowable expenses. This is one of the most misunderstood areas, so let’s break it down:

Common Allowable Expenses

• Letting agent fees and management charges.
• Accountant fees for preparing property accounts.
• Repairs and maintenance (but not improvements).
• Insurance (landlord, buildings, contents).
• Council tax, utility bills, and ground rent (if paid by landlord).
• Service charges.
• Replacement of domestic items (furniture, white goods, etc.).
• Mileage or travel costs to and from the property.

What You Cannot Claim

• The full mortgage repayment (only the interest portion is deductible, and even that is restricted to a 20% tax credit under Section 24 rules).
• Capital improvements (e.g., adding an extension).
• Personal costs (e.g., your own home’s bills).

HMRC resource: Expenses you can claim as a landlord

Step 4: Completing the Self-Assessment Return

When you log into your Self-Assessment account, you’ll complete the main SA100 form, plus the SA105 property pages (for UK property income).

Key details you’ll need to enter:

• Total rental income received.
• Allowable expenses (itemised).
• Net rental profit or loss.
• Mortgage interest relief (20% credit).
• Any property losses brought forward.
• Capital allowances (if furnished holiday lets apply).
• Tax already deducted (e.g., non-resident landlords scheme).

If you jointly own property, you must only declare your share of the income and expenses.

Step 5: Deadlines and Payment

• 5 October – Deadline to register for Self-Assessment.
• 31 October – Deadline for paper tax returns.
• 31 January – Deadline for online tax returns (for the tax year ending the previous April).
• 31 January – Deadline for paying tax owed.
• 31 July – Second Payment on Account deadline (if applicable).

Example: For the tax year 6 April 2024 – 5 April 2025:

• Online filing deadline: 31 January 2026.
• Payment deadline: 31 January 2026 (plus possible payment on account).

HMRC deadlines: Self-Assessment deadlines

Step 6: Payments on Account (POA)

If your tax bill is more than £1,000 and less than 80% is collected at source, HMRC may require Payments on Account.

This means:

• 50% of the expected next year’s bill is due 31 January.
• Another 50% is due 31 July.

This often surprises new landlords, as you could be paying 150% of your first bill in one go. Planning cash flow is essential.