For landlordsReady
Flat 4, Marlow RoadSA105 UK property
- Letting agent, March+£1,200.00ReviewRent
- Mortgage interest£412.50ReviewFinance costs
- Gas safety certificate£85.00ReviewRepairs & upkeep
If you let a property, four figures give you a rough bill, with the mortgage interest rule applied. The return itself comes from your records: upload your agent’s statement or a bank statement, answer the few lines it can’t place, and file. One file per property.
Your share if the property is jointly owned.
Agent fees, repairs, insurance, safety checks, ground rent. If it’s under £1,000 we use the property allowance instead.
Interest only, not the capital. It isn’t a cost; it earns a 20% reduction instead.
Before tax, for the year. It decides which band your rental profit falls into.
Nothing you type is saved or sent anywhere.Estimated tax on your rental income£0Type your figures and the number appears.
Tax before the interest reduction£0.00
Reduction for mortgage interest£0.00
Of every £1 of profit0p
Uses 2025/26 income tax rates for England, Wales and Northern Ireland. No National Insurance is due on rent. It’s an estimate, not advice. The bill is due 31 January.
What comes off the rent, and what doesn’t.
Two rules decide your profit.
Rent in, costs out
Costs you can take off the rent: letting agent fees, repairs and maintenance, insurance, gas and electrical safety checks, ground rent and service charges, council tax and bills you pay while the property is empty, and your accountant. Improvements that add value, such as an extension, aren’t costs; they count against capital gains when you sell.
If your costs come to under £1,000 you can take the £1,000 property allowance instead. Swiftmore picks whichever leaves you better off.
Check a specific cost →Mortgage interest is different
Since April 2020 you can’t take the interest on a residential let off as a cost. Instead HMRC takes 20% of the interest off your tax bill, capped at the lowest of the interest itself, your property profit, and your income above the personal allowance. If you pay higher-rate tax you feel the difference most. The reduction stays at 20% in Scotland even though the Scottish bands differ. Swiftmore asks what interest you paid and puts it through the rule for you.
Two more things to get right.
Who owns it, holiday lets, and the digital rules on their way.
Jointly owned and furnished lets
If you own the property with someone else, enter your share of the rent and costs. Married couples and civil partners split it evenly unless they’ve told HMRC otherwise. Furnished holiday lets lost their separate rules in April 2025 and are now taxed like any other let.
Making Tax Digital reaches property income too
Qualifying income adds your rent to any self-employment income, before costs, so a rental on its own can take you over the line.
Check your MTD date →
What Swiftmore files for you.
Your main return (the SA100) and the UK property pages (the SA105), with the finance cost box filled from the interest you paid, plus the employment page if you also have a job. Any number of properties at no extra cost, each in its own section of the one return.
Start free£99 when you file. No card to start.
Start freeFree to keep records. £99 for a tax year you read and file. No card to start.