SA105 form

The SA105 form is the “UK property” supplementary pages you attach to your Self Assessment tax return when you have UK property income (most commonly rent from a rental property). It sits alongside the main SA100 and is where HMRC expects you to declare your rental income, allowable expenses and the resulting rental profit or loss.

From a landlord’s point of view, SA105 is the place you turn your day-to-day letting activity into a tax calculation. You’ll typically include, total rent received, any other amounts charged to the tenant for services, and then deductible expenses such as letting agent fees, insurance and qualifying repairs, as distinct from improvements. You’ll also choose whether to use the property allowance instead of claiming actual expenses, if that’s better for you. HMRC’s current SA105 layout explicitly includes a box for property income allowance (the £1,000 rule) and a tick box if you’re using traditional accounting rather than the cash basis.

A few practical watch-outs that commonly affect landlords:

Jointly owned property: if you receive rental income jointly, for example with a spouse, you still need to reflect the correct split and keep records that support it.
Finance costs: mortgage interest relief is restricted for individuals, so the figures you enter on SA105 can affect your tax position in non-obvious ways, especially with an interest only mortgage.
Capital vs revenue: items that feel like “maintenance” may be treated as improvements for tax. Capital allowance rules are different again, so good invoices and descriptions matter.

The Renters’ Rights Act doesn’t change the SA105 itself, but it can affect your numbers: more structured rent review rules, limits around rent in advance, and higher compliance expectations can change cashflow and costs, so keeping clean records throughout the tenancy is now even more valuable.

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