Corporation Tax (Ireland)

Companies tax-resident in Ireland pay corporation tax on their worldwide profits; non-resident companies pay only on profits attributable to an Irish branch or agency (TCA 1997). Since 2015 an Irish-incorporated company is treated as Irish-resident by default, unless a double taxation treaty allocates residence to another jurisdiction.

The 12.5% headline rate applies to income from an active trade genuinely carried on in Ireland — people, decision-making and regular commercial operations, the classic badges of trade. Since 2024, groups with consolidated revenue of €750 million or more are additionally subject to the 15% Pillar Two minimum effective rate via a top-up tax.

Non-trading, passive income under Cases III, IV and V of the TCA 1997: rental income from Irish land and buildings, interest, and most foreign dividends. If a close company retains such income instead of distributing it within 18 months, a further 20% close company surcharge can apply on the undistributed amount.

Small companies — a prior-year liability of €200,000 or less — pay one instalment, the lower of 90% of the current-year estimate or 100% of the prior-year liability, by day 23 of the month before the period ends. Large companies pay in two instalments, in months six and eleven. The CT1 return follows within nine months.

No. Companies pay tax on chargeable gains at the 33% capital gains rate, computed separately with its own indexation and relief rules, even though it is collected through the corporation tax return. Only trading income and passive income streams belong in this simulator; disposals of assets or shares require a dedicated CGT computation.

Applying 12.5% to the whole accounting profit. Rental and investment income is carved out at 25%, accounting depreciation must be replaced by capital allowances, and undistributed passive income in a close company can trigger the 20% surcharge. Missing a preliminary tax deadline also exposes the company to interest at roughly 8% per annum.