A guide to self-assessment

Overview

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

For Capital 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.

For more information on filling out the Form 11, please see Filing your tax return.

Most individuals must file their Form 11 online, through the Revenue Online Service (ROS). There is more information on Mandatory electronic payment of taxes and filing of tax returns in the Starting a Business section.

Next: Who should register for Income Tax self-assessment?