A guide to self-assessment


This guide sets out the basic principles of the self-assessment system as it applies to Income Tax (IT).

For Captial Gains Tax (CGT), please refer to the CGT section. 
For Corporation Tax (CT), please refer to the Companies and charities section.

Under Self-Assessment there is a common date for the payment of tax and filing of tax returns. You must file your tax return on or before 31 October in the year after the year to which the return relates. 

This system, which is known as Pay and File, requires you to:

  • file your return for the previous year
  • make a self-assessment for that year
  • pay the balance of tax for that year
  • pay preliminary tax for the current year.

You must self-assess when filing your annual tax return. An exception is made where you file a paper return on or before 31 August in the year after the year to which the return relates.

You must file Form 11 online through the Revenue Online Service (ROS). For more information on filling out the Form 11 please see Filing your tax return.

Next: Who should register for self-assessment?