The Irish corporation tax system operates on a self-assessment basis.  Therefore, it is solely the responsibility of the company to calculate and pay its corporation tax liability within deadline.

Any company liable to corporation tax must submit a CT1 Form which is a Tax Return containing details of profits, chargeable gains and other relevant information as outlined in Section 884 TCA 1997.

This return must be filed within nine months of the end of the company’s accounting period but no later than the 23rd day of the month if the Tax Return along with payment of the associated tax liability is filed via the Revenue Online Service.  Otherwise, the Return must be filed within eight months and twenty one days of the company’s year-end.

Consequences of filing a late or incomplete/incorrect CT Return

If a company files (a) an incomplete or (b) an incorrect or (c) a late CT1 Form the following surcharges will apply:

• If filed less than two months late, a 5% surcharge (subject to maximum of €12,695) will be calculated on the company’s CT liability for the accounting period in question.  This surcharge will apply irrespective of whether the tax had been paid within deadline because this surcharge arises in relation to the late filing of the CT1 Form.
• If filed more than two months late, a 10% surcharge (subject to maximum of €63,485) will be levied on the company’s tax liability for the period in question regardless of whether or not the tax had been paid on time.

Please be aware that the surcharge also includes any Income Tax due.

In addition to the above surcharges, in circumstances where a company does not submit its return on time, the following restrictions on the use of certain allowances and reliefs will also apply:

• If filed less than two months late, the reliefs and allowances will be restricted by 25%, subject to a maximum of € 31,740 in each case
• If filed later than two months, the reliefs and allowances are restricted by 50%, subject to a maximum of € 158,715 in each case.

For Group Relief to apply, both the surrendering and the claimant company must have submitted their Corporation Tax Returns within the deadline date.

In situations where the Corporation Tax Return has been filed on time but the Local Property Tax (LPT) Return or relevant payment is outstanding at the CT filing date then a surcharge of 10% will be levied on the final liability.

This surcharge will also be levied if an agreed payment arrangement for LPT has not been set up.

If the company subsequently pays its LPT liability in full, bringing its tax affairs up to date, the amount of the surcharge will be capped at the amount of the LPT liability involved.