The SA105 is the “UK property” supplementary page you attach to your Self Assessment to declare rental income. If you let property as an individual, this is where your rental profit — and the tax on it — is worked out. Here’s who needs it, what you can and can’t deduct, how the Section 24 mortgage rules bite, and the deadlines that matter.
The SA105 is the supplementary page of the Self Assessment return (SA100) used to report income from UK land and property. It covers residential and commercial lettings, furnished and unfurnished — furnished holiday lettings have their own separate rules.
You combine the figures for your UK residential properties, totalling income and allowable expenses to arrive at a single taxable profit or loss for the year.
Income is the rent and related charges you receive. From that you deduct allowable, wholly-and-exclusively revenue expenses such as:
For residential lets, mortgage interest and other finance costs are no longer a deductible expense. Instead you get a finance-cost tax reducer worth 20% of the interest.
For higher- and additional-rate taxpayers this is far less generous than the old full deduction — which is a major reason some landlords move properties into a limited company (see our CT600 guide).
Usually yes — and it’s worth it. Reporting a rental loss lets you carry it forward to set against future rental profits.
A tax-free allowance for property income. If your gross rental income is £1,000 or less it’s usually tax-free; above that you can deduct your actual expenses or claim the £1,000 allowance instead — whichever leaves you better off.
Only the interest counts, and for residential lets it’s no longer a straight deduction — it’s a 20% basic-rate tax reducer under Section 24. Capital repayments are never deductible.
Each owner declares their share of income and expenses on their own return. Married couples and civil partners are taxed 50/50 by default unless they make a valid Form 17 declaration reflecting actual ownership.
It’s part of your Self Assessment: 31 October for paper filing, and 31 January for online filing and payment.
This guide is general information, not tax advice. Tax rules, rates and allowances change frequently — check GOV.UK and speak to a qualified accountant for your own circumstances.
PropertyApp maps your income and expenses to the right SA105 boxes, handles joint ownership and Section 24, and lets you lock the year and email your accountant. Free for up to 3 properties.
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