Ireland’s 12.5% corporate tax rate pulls companies in. The compliance layer is where finance teams get burned. Corporation tax return deadlines, preliminary tax instalments, Pillar Two top-up rules, and close company surcharges each carry their own penalties for a wrong move.
This guide covers the rates, residency tests, filing mechanics, deadlines, reliefs, withholding taxes, and capital gains that shape an Irish corporate tax position. Every figure is verified against the Revenue Commissioners (Revenue).
What Is the Corporate Tax Rate in Ireland?
Ireland charges 12.5% corporation tax on trading income and 25% on non-trading (passive) income such as rental, investment, and certain foreign income, per Revenue’s basis of charge guidance. Corporation tax is levied only at national level by Revenue. There is no state, regional, or municipal corporate tax layer.
| Income or activity | Rate | Source |
|---|---|---|
| Trading income | 12.5% | Revenue (basis of charge) |
| Non-trading (passive) income | 25% | Revenue (basis of charge) |
| Petroleum and mineral extraction | 25% to 40% | Revenue (Petroleum Production Tax) |
| Chargeable gains (see CGT section) | 33% | Revenue (capital gains for companies) |
| Pillar Two minimum, groups of €750M or more (see Pillar Two section) | 15% | Revenue (Pillar Two) |
Petroleum profits carry the 25% rate plus a Petroleum Production Tax that climbs with a field’s profit ratio to an overall marginal take of up to 40%, per Revenue and reporting in the Irish Times.
How Does the OECD Pillar Two 15% Minimum Tax Work in Ireland?
Groups with consolidated revenue of €750 million or more in at least two of the preceding four years face a 15% minimum effective tax rate, per Revenue’s Pillar Two rules. The rules apply to accounting periods beginning on or after 31 December 2023, under Ireland’s transposition of the EU (European Union) Minimum Tax Directive. Companies below the threshold still pay 12.5%.
The regime works through the OECD (Organisation for Economic Co-operation and Development) global minimum tax framework, using three mechanisms.
| Mechanism | What it does | Effective from | Source |
|---|---|---|---|
| Income Inclusion Rule (IIR) | Parent pays top-up tax on low-taxed subsidiaries | Periods from 31 Dec 2023 | Revenue (Part 4A TCA 1997) |
| Qualified Domestic Top-up Tax (QDTT) | Ireland collects the top-up on domestic profits itself | Periods from 31 Dec 2023 | Revenue (Part 4A TCA 1997) |
| Undertaxed Profits Rule (UTPR) | Backstop reallocating top-up where no IIR applies | Periods from 31 Dec 2024 | Revenue (Part 4A TCA 1997) |
Ireland now runs a two-tier system: 12.5% for everyone below €750 million, a 15% floor above it. The QDTT is fully creditable against IIR or UTPR liability, so Ireland keeps the top-up rather than ceding it to another jurisdiction, per Revenue’s Part 4A guidance.
What Is the Effective Tax Rate for Companies in Ireland?
Ireland’s headline rate is 12.5%, but reliefs push the effective rate lower for qualifying companies, per Revenue. The research and development credit, the Knowledge Development Box, and capital allowances all reduce tax paid. Pillar Two then sets a 15% effective floor for groups above €750 million.
Most small and mid-sized companies pay close to the 12.5% trading rate. The reliefs section below sets out how each one lowers the effective rate.
When Is a Company Tax Resident in Ireland?
A company is Irish tax resident if it is incorporated in Ireland or centrally managed and controlled here, per Revenue’s company residency rules. Companies incorporated on or after 1 January 2015 are automatically resident. The incorporation test closed the Double Irish structure, with grandfathered arrangements ending 31 December 2020.
Non-resident companies are taxable on Irish-source trading income earned through a branch or permanent establishment (PE), per Revenue.
How Do You File a Corporation Tax Return in Ireland?
File Form CT1, the corporation tax return, electronically through the Revenue Online Service (ROS); e-filing is mandatory, per Revenue. Companies also file Form 46G for third-party payments and, where required, iXBRL (inline eXtensible Business Reporting Language) tagged accounts. Payment is electronic via ROS.
| Filing | What it is | Who must file | Source |
|---|---|---|---|
| Form CT1 | Corporation tax return | Every company liable to corporation tax | Revenue |
| Form 46G | Return of third-party payments | Companies making reportable payments to contractors and professionals | Revenue |
| iXBRL accounts | Tagged financial statements | Large Cases Division companies mandatory; small companies under Companies Act size thresholds may be exempt | Revenue |
Keep finalised financial statements, tax computations, capital allowance and loss records, and preliminary tax records to support every return.
What Are Ireland’s Corporate Tax Filing Deadlines?
The CT1 is due nine months after the accounting period ends, by the 23rd day of that month via ROS, per Revenue’s payment and filing guidance. A 31 December 2024 year-end means the CT1 is due 23 September 2025. Preliminary tax falls due earlier, and the schedule depends on company size.
| Obligation | Timing | Source |
|---|---|---|
| CT1 return and balance of tax | 9 months after period end, by the 23rd | Revenue |
| Small company preliminary tax (prior-year liability €200,000 or less) | 100% of prior year or 90% of current year, by 23rd of month 11 | Revenue |
| Large company first instalment (liability over €200,000) | 45% of current year or 50% of prior year, by 23rd of month 6 | Revenue |
| Large company second instalment | Brings total to 90% of current year, by 23rd of month 11 | Revenue |
The €200,000 prior-period liability threshold decides whether a company is small or large for preliminary tax, not the month its year ends.
What Are the Penalties for Late Corporation Tax Filing in Ireland?
Late filing triggers a surcharge of 5% of the tax due if up to two months late, capped at €12,695, or 10% beyond two months, capped at €63,485, per Revenue. Interest on unpaid tax runs daily at 0.0219%, roughly 8% a year. Late filing also restricts loss relief and group relief.
| Penalty | Amount | Source |
|---|---|---|
| Interest on late payment | 0.0219% per day (about 8% annually) | Revenue |
| Late filing surcharge, up to 2 months | 5% of tax due, capped €12,695 | Revenue |
| Late filing surcharge, over 2 months | 10% of tax due, capped €63,485 | Revenue |
For loss-making groups, the relief restriction can cost more than the surcharge itself. It caps the value of losses and group relief claimed on the late return.
What Is the Close Company Surcharge in Ireland?
A close company, controlled by five or fewer participators or by participator-directors, pays a 20% surcharge on undistributed investment and rental income, per Revenue. Close service companies pay 15% on undistributed professional income. The surcharge applies only if profits stay undistributed beyond an 18-month window after the accounting period ends.
A small de minimis amount is exempt before the surcharge bites. Companies that distribute the relevant income within 18 months usually avoid it entirely.
What Corporate Tax Reliefs and Exemptions Are Available in Ireland?
Ireland’s main corporate tax reliefs are the R&D tax credit, the Knowledge Development Box, capital allowances, the foreign-dividend participation exemption, start-up relief, and loss relief, per Revenue. Together they cut the effective rate for qualifying companies below 12.5%. Each has its own rate, effective date, and conditions.
| Relief | Rate or benefit | Effective date | Source |
|---|---|---|---|
| R&D tax credit | 30% of qualifying expenditure | Periods from 1 Jan 2024 | Revenue |
| Knowledge Development Box (KDB) | 10% effective rate on qualifying IP income | From 1 Oct 2023 | Revenue |
| Participation exemption | Full exemption for qualifying foreign dividends | Distributions from 1 Jan 2025 | Revenue |
| Start-up relief (Section 486C) | CT relief for first 5 years, PRSI-capped | Trades from 1 Jan 2018 (carry-forward) | Revenue |
| Wear-and-tear allowances | 12.5% per year over 8 years on plant and machinery | Ongoing | Revenue |
How does the R&D tax credit work?
The research and development (R&D) tax credit is worth 30% of qualifying expenditure for accounting periods commencing on or after 1 January 2024, up from 25%, per Revenue’s R&D credit guidance. Companies without enough tax liability receive it in cash over three years. The first-year payable threshold rose from €25,000 to €50,000.
Qualifying activity must be systematic, investigative, or experimental work seeking a scientific or technological advance.
What is the Knowledge Development Box?
The Knowledge Development Box (KDB) taxes income from qualifying intellectual property (IP) developed in Ireland at a 10% effective rate, per Revenue. The rate rose from 6.25% to 10% under Finance Act 2022, effective 1 October 2023, to align with Pillar Two. The KDB is an OECD-compliant patent box for qualifying IP.
What capital allowances can Irish companies claim?
Irish companies claim wear-and-tear allowances on plant and machinery at 12.5% a year over eight years, per Revenue. Industrial buildings allowances cover qualifying structures. Capital Allowances for Intangible Assets (CAIA) give relief for acquired intellectual property, spreading the cost against income from that IP.
What is the participation exemption for foreign dividends?
Since 1 January 2025, qualifying foreign dividends from EU, EEA, or treaty-country subsidiaries are exempt from Irish corporation tax, per Revenue’s participation exemption guidance. The parent must hold at least 5% of the subsidiary for a continuous 12 months. The exemption replaces credit-method relief with a simpler distribution-level exemption. EEA means the European Economic Area.
What start-up relief is available under Section 486C?
Section 486C gives new trading companies relief from corporation tax for their first five years, per Revenue. Full relief applies where annual corporation tax is €40,000 or less, with marginal relief between €40,000 and €60,000. The relief is capped by reference to employers’ Pay Related Social Insurance (PRSI), at €5,000 per employee.
How does loss relief work?
Trading losses offset against current-period profits first, then carry back one year against the same trade, per Revenue. Unused trading losses carry forward indefinitely against future profits of the same trade. Groups with 75% common ownership can surrender losses between members through group relief.
What Withholding Taxes Apply in Ireland?
Ireland applies withholding tax on several outbound payments, with wide exemptions for EU and treaty residents, per Revenue. Dividends carry 25%, interest and patent royalties 20%, and non-resident landlord rent 20%. Relevant Contracts Tax (RCT) applies to construction, forestry, and meat processing.
| Payment type | Rate | Key exemptions | Source |
|---|---|---|---|
| Dividends | 25% | EU and treaty parent companies | Revenue |
| Interest to non-residents | 20% | EU, treaty, quoted eurobonds | Revenue |
| Patent royalties | 20% | EU and treaty; other royalties generally exempt | Revenue |
| Non-resident landlord rent | 20% | Collection-agent arrangements | Revenue |
| Relevant Contracts Tax (RCT) | 0% / 20% / 35% | Compliant subcontractors qualify for 0% | Revenue |
How Are Capital Gains Taxed for Irish Companies?
Chargeable gains are taxed at an effective 33%, not the 12.5% trading rate, per Revenue’s capital gains for companies guidance. Companies gross up the gain so the corporation tax charge matches what Capital Gains Tax (CGT) would have been. This catches finance teams out in mergers and acquisitions (M&A) and asset disposals.
The Section 626B participation exemption can fully exempt gains on disposals of qualifying shareholdings in trading subsidiaries, per Revenue. Entrepreneur Relief and indexation for pre-2003 acquisitions remain available.
How Do Ireland’s Tax Treaties Prevent Double Taxation?
Ireland has signed more than 70 double taxation agreements, per Revenue. These treaties cut or remove withholding tax and provide credit or exemption relief on the same income. A company earning cross-border income uses the relevant treaty to avoid paying tax twice on the same profits.
How Commenda Helps With Corporate Tax in Ireland
Commenda’s corporate tax and bookkeeping platform tracks your Irish filing calendar, including the CT1, preliminary tax, and Form 46G, and prepares and files each return so nothing slips. It confirms every required filing is handled, so your controller closes the laptop at 6 rather than reopening it at 8.
Map every Irish deadline in one place with Commenda’s compliance calendar, and keep wider obligations on track with our guide to annual compliance for Irish businesses.
Book a demo for a walkthrough of your Irish filing calendar and relief eligibility.
