Revenue eBrief No. 203/25

30 October 2025

Completion of Corporation Tax Returns Form CT1 2025

A new Tax and Duty Manual (TDM) Part 38-02-01J - Completion of Corporation Tax Returns Form CT1 2025 - has been created.

This TDM contains information about how to access help in completing the ROS Form CT1, and it contains updates about the 2025 Form CT1.

The Corporation Tax Return for accounting periods ending in 2025 is available since April 2025: for filing through ROS online and the ROS Return Preparation Facility (RPF). Further updates to the Form CT1 2025 were released in June 2025.

This TDM includes the following updates for 2025.

• Updates to the Company Details panel (paragraph 1) including De Minimis Aid and Transfer Pricing.
• Updates to the Trading Results panel (paragraph 2) including a new section for lease taxation section 403/404.
• Changes to the Extracts from Accounts panel (paragraph 3) including text changes for iXBRL filing and Expenses and Deductions for Stock Exchange Listings Expenditure.
• Changes to the Irish Investment and Other Income panel (paragraph 4) for R&D clawback .
• Changes to the Foreign Income panel (paragraph 5) relating to Foreign Life Policies and Offshore Funds.
• Changes to the Deductions, Reliefs and Credits panel (paragraph 6) relating to Stock Exchange Listing Expenditure.
• Changes to the Research and Development panel (paragraph 7) including unused carry forward, section 766C and S766D.
• Changes to the Film Tax panel (paragraph 8) for the Scéal Enhanced Credit.
• Clarification around certain fields relating to Lease Taxation