Do I need to register for Self Assessment? You need to register if you have untaxed income, such as self-employment, rental income, or earnings over certain limits. Registration must be done before you can submit a tax return. Who needs to file a Self Assessment tax return? Self-employed individuals, company directors, landlords, and people with additional income not taxed through PAYE usually need to file a return. When is the Self Assessment deadline? The online filing dead