Your company’s next deadlines, from one date
An Irish company files its CT1 by the 23rd of the ninth month after its year-end. A UK company pays corporation tax 9 months and 1 day after year-end and files its CT600 within 12 months. A Gibraltar company files its CT1 nine months after the end of the month its period ends. Enter your year-end to see your own dates.
Your company’s financial year-end
Shown on the CRO register, and separate from your year-end
Your dates
Preliminary tax (small companies)
Paid by the 23rd of the eleventh month of the accounting period. Larger companies pay in two instalments.
CT1 return and balance of tax
Filed and paid through ROS by the 23rd of the ninth month after the period ends.
Estimates for standard periods. First accounting periods, unusual period ends, group companies and large-company instalments can change these dates.
How it’s worked out
The rules behind the figure, one country at a time.
The CT1 and any balance of tax are due through ROS on the 23rd of the ninth month after the period ends. Small companies pay preliminary tax by the 23rd of the eleventh month of the period. The CRO B1 is due within 56 days of the Annual Return Date, which is set separately from the year-end.
Frequently Asked Questions
Written and maintained by the Shiel Accountants team. Last updated .
Can I add these dates to my calendar?
Yes. Use the Add to calendar button to download the dates as a calendar file with a reminder two weeks before each one.
What if this is my company’s first year?
First accounting periods can be longer or shorter than 12 months and the first accounts deadline is often different, so ask us to confirm your dates.
What happens if I miss a deadline?
Each country charges late filing penalties or surcharges, and in Ireland a late B1 can cost the company its audit exemption. If you are already late, tell us and we will prioritise the filing.
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