If you are an individual and own property in the UK that you have rented out, you are liable to file a self-assessment tax return of yourself. You have to register yourself for self-assessment at any time during or after the period in which you earn property income. The income tax for Landlord is same as for other self-employed or sole trader businesses i.e. 6th April to 5th April. This is the period for which you have to disclose your property income to HMRC through self-assessment return.