How do I pay tax on rental income as an accidental landlord?

How do I pay tax on rental income as an accidental landlord? If you do not already send a tax return, register for Self Assessment by 5 October after the tax year letting starts. For rent first received in 2026-27, register by 5 October 2027 and file online by 31 January 2028. If you do not usually send a tax return, register for Self Assessment by 5 October after the end of the tax year in which you had the rental income. For rent that starts in the 2026-27 tax year, that is 5 October 2027. Not as an expense if you own the property personally. Instead, for 2026-27 you get a tax reduction of 20% of the lower of your finance costs, your property profits or your income above the Personal Allowance. From 2027-28 the reduction is 22%. Yes. GOV.UK says that if you have a mortgage on a property you want to rent out, you must get permission from your mortgage lender. Read the full answer, with every source, at rightotax.co.uk.