Corporation tax in Ireland: rates, payment dates and reliefs

Companies pay 12.5% on trading profit and 25% on rent and investment income. How preliminary tax works, and what Budget 2027 changes.

Irish companies pay corporation tax on their profits for each accounting period, normally a year. The rate depends on where the income comes from.

The rates

Groups with worldwide revenue of €750 million or more pay at least 15% overall under the Pillar Two rules. Capital gains are taxed separately.

An example

A company with a year ending 31 December 2026 makes €120,000 of trading profit. It claims €10,000 of capital allowances (equipment costs written off over several years) and earns €2,000 in deposit interest:

When to pay

Most of the tax is paid before the year ends, as preliminary tax. A small company is one whose tax for the previous period was no more than €200,000. It pays the lower of 90% of this year's tax and 100% of last year's. It pays in one go, by the 23rd of the month before the year ends. Larger companies pay in two instalments. A new company owing under the limit in its first period pays no preliminary tax.

For the example, with €12,000 owed for 2025, preliminary tax of €12,000 is due by 23 November 2026. The corporation tax return (Form CT1) and the balance of €2,250 are due by 23 September 2027. That is nine months after the year end, by the 23rd, through ROS.

Reliefs worth knowing

• Start-up relief (section 486C): new companies can reduce corporation tax on the trade for their first 5 years, up to the employer's PRSI they pay. The relief is full where tax is €40,000 or less, and partial up to €60,000.
• R&D tax credit: 35% of qualifying spend where the return is due on or after 23 September 2027, 30% before, set against tax or paid out. See R&D tax credit.
• Close company surcharge: owner-managed companies that keep rent and investment income in the company pay an extra 20%. See close company surcharge.

Budget 2027

• The small company limit for preliminary tax rises from €200,000 to €350,000.
• Preliminary tax will be met if 80% is paid by the last instalment date and the rest within four months of the year end.
• Start-up relief is extended to new companies starting to trade by 31 December 2030.
• The Knowledge Development Box is extended to 1 January 2032, and the R&D credit is enhanced.

These take effect when Finance (No. 2) Bill 2026 is enacted.

To work out your company's tax, preliminary tax and dates, use the corporation tax calculator.

Work it out

• Corporation tax for your company →
• Salary or dividends from your company →
• R&D tax credit →

Sources

• Revenue: Corporation Tax: basis of charge (12.5% trading, 25% non-trading and excepted trades) (checked 25/10/2026)
• Revenue: Preliminary Corporation Tax (small companies: €200,000; 90% / 100% rules) (checked 25/10/2026)
• Revenue: When is preliminary Corporation Tax due? (23rd of month 11; large companies months 6 and 11) (checked 25/10/2026)
• Revenue: Corporation Tax payment and filing (CT1 and balance by the 23rd of month 9) (checked 25/10/2026)
• Revenue: Tax and Duty Manual Part 15-03-03: tax relief for new start-up companies (s.486C) (checked 24/10/2026)
• Revenue: What are the Pillar Two rules? (15% minimum effective rate for groups with revenue of €750 million or more) (checked 16/10/2026)
• Department of Finance: Budget 2027 Tax Policy Changes (section 2.2: taxation of investments; chapter 9: Investment Account) (checked 25/10/2026)

General information, not tax advice. HeyPenny is not a tax agent.