Income tax: Form 11
If you are self-employed, a proprietary director, or have significant non-PAYE income, you file a Form 11 under self-assessment. The deadline for the 2025 tax year is Saturday 31 October 2026, extended to Wednesday 18 November 2026 where you file the return and pay the liability through ROS.
The ROS extension requires both actions. File on ROS but pay by another method, or pay on ROS and file on paper, and you lose the extension entirely and revert to 31 October.
On that date you settle two things: the balance of income tax, USC and PRSI for 2025, and preliminary tax for 2026. Preliminary tax is normally the lower of 90% of the current year's expected liability or 100% of the prior year's.
What a late Form 11 costs
| How late | Surcharge |
|---|---|
| Filed within two months of the deadline | 5% of the tax due, capped at €12,695 |
| Filed more than two months late | 10% of the tax due, capped at €63,485 |
The surcharge is calculated on the tax due before deducting payments already made, which means you can owe a surcharge on a return where you have already paid everything. Interest on late payment runs separately and daily.
Corporation tax: CT1
A company files its CT1 and pays any balance nine months after the end of its accounting period. Where the period ends on or after the 21st of a month, the return is due by the 21st of the ninth month following; filing and paying through ROS extends that to the 23rd.
For a company with a 31 December 2025 year end, that means 23 September 2026 on ROS.
Preliminary corporation tax
Preliminary corporation tax is paid before the accounting period ends, not after it. Small companies — broadly those with a prior-year liability not exceeding €200,000 — pay 100% of the prior year's liability in a single instalment by the 23rd day of the month preceding the period end. Large companies pay in two instalments, the first in month six.
A late CT1 carries the same 5% and 10% surcharge structure as the Form 11, and can also restrict the company's ability to use losses and group relief.
VAT
Most VAT-registered businesses file a VAT3 every two months, covering January–February, March–April and so on. The return and payment are due by the 19th of the month following the period end, extended to the 23rd when both are done through ROS.
- Revenue may assign a four-monthly, six-monthly or annual cycle where liabilities are small.
- An annual Return of Trading Details is due after the VAT year end, and must reconcile to your VAT3s.
- Businesses registered for intra-EU supplies file VIES statements, monthly or quarterly depending on volume.
Payroll
PAYE operates in real time. A payroll submission must reach Revenue on or before the date employees are paid, not at the end of the month. The monthly PAYE liability is then due by the 14th of the following month, extended to the 23rd on ROS.
Companies Registration Office: B1 annual return
Every Irish company has an Annual Return Date, and the B1 must be filed within 56 days of it, with financial statements attached for all returns after the first.
| Consequence | Detail |
|---|---|
| Late filing fee | €100 on the day after the deadline, then €3 per day, capped at €1,200 per return |
| Loss of audit exemption | Where the annual return is filed late more than once in a five-year period |
| Enforcement | Prosecution of the company and its directors, or involuntary strike-off |
Capital gains tax
CGT payment comes before the return. Tax on disposals made between 1 January and 30 November is due by 15 December of the same year. Tax on disposals in December is due by 31 January following. The CGT return itself is due by 31 October of the year after the disposal.
A working calendar
| When | What |
|---|---|
| 14th monthly (23rd on ROS) | PAYE/PRSI/USC liability for the previous month |
| 19th bi-monthly (23rd on ROS) | VAT3 return and payment |
| 23rd of the 9th month after year end | CT1 return and balance of corporation tax |
| 23rd of the month before year end | Preliminary corporation tax, small companies |
| Within 56 days of the Annual Return Date | B1 annual return and financial statements |
| 15 December | CGT on disposals from 1 January to 30 November |
| 31 January | CGT on December disposals |
| 31 October (18 November on ROS in 2026) | Form 11, balance for the prior year and preliminary tax |