How to complete a Company Tax Return

Use this guide to help you complete form CT600 (2018) version 3.


How to complete a Company Tax Return

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This guide will help you complete the Company Tax Return CT600 (2018) version 3.

You should read all the general notes and use the box-by-box advice when you’re completing the form.

Published 7 April 2015
Last updated 26 October 2018 + show all updates
  1. The guidance for Loss Reform and Corporate Interest Restriction (CIR) to help companies file their Company Tax Return has been updated.
  2. The guidance has been updated with information relating to the number of 51% companies and clarification of the supplementary charge rate.
  3. The PDF has been updated to correct parts of the CT600 guide (2018).
  4. The guide has been updated to clarify parts of the CT600 form.
  5. New CT600 guide (2018) version 3 added.
  6. CT600 guide (2017) has been updated to include the new loss reform rules that apply for periods ending on or after 1 April 2017.
  7. New CT600 guide (2017) version 3 added.
  8. CT600_Guide_V3. replaced by CT600_Guide _V0.1
  9. First published.