This track is for accountants and advisors who prepare or review R&D tax credit claims for Irish clients. Ireland's R&D corporation tax credit gives companies a credit against corporation tax for qualifying R&D expenditure, administered by the Revenue Commissioners, and credit that cannot be used is paid out in three instalments. Revenue divides every claim into a science test and an accounting test. Three features change the practitioner's work: a pre-filing notification at least 90 days before a first claim, a 12 month claim limit with no late claims, and the instalment arithmetic.
How the Ireland rules change the program
| Module | What is different in Ireland | Country page |
|---|---|---|
| Legislation and guidance | Taxes Consolidation Act 1997 sections 766, 766A and 766C; the 2004 Regulations (S.I. No. 434 of 2004); Revenue's Tax and Duty Manual Part 29-02-03. | Revenue guidelines |
| Eligibility analysis | The science test: activities in a prescribed field that are systematic, investigative or experimental, seek scientific or technological advancement, and resolve scientific or technological uncertainty that a competent professional could not readily resolve. | Science test |
| Advanced calculations | 30% of qualifying expenditure for accounting periods beginning on or after 1 January 2024; 35% where the corporation tax return filing date is on or after 23 September 2027. Subcontracting caps, grant-assisted expenditure excluded, three instalments. | Eligible expenditure |
| Technical interviews | Revenue may consult an expert in the relevant field, having first notified the company, and the expert may be given access to the company's records and personnel. | Documentation |
| Reports and narratives | The Form CT1 R&D panel records qualifying expenditure, the credit claimed and the treatment of each instalment; no technical report is filed. Revenue expects contemporaneous documentation for both tests, including timesheets, invoices and a reconciliation of the claim to the accounts. | How to claim |
| Disputes and audits | The Code of Practice for Revenue Compliance Interventions: Level 1 compliance support, Level 2 risk reviews and audits, Level 3 investigations. Penalties for a deliberate or careless default are 100, 40 or 20 percent of the tax, reduced for cooperation and qualifying disclosures. | Revenue audits |
| Ethics, integrity and fee arrangements | A qualifying disclosure made before a Level 2 intervention begins reduces the penalty and prevents publication in the list of tax defaulters. Whether contingent fees are permitted depends on the professional body the advisor belongs to; see knowyourfees.org. | Why claim integrity matters |
Forms and deadlines
| Form or step | Deadline or rule | Country page |
|---|---|---|
| Pre-filing notification | Companies claiming for the first time, or that have not claimed in the previous 3 years, must notify Revenue at least 90 days before the claim, using a prescribed form through Revenue Online Service. A claim made without the required notification is not a valid claim. | How to claim |
| Form CT1 | Due by the 23rd day of the ninth month after the end of the accounting period where filed electronically. | Deadlines |
| The R&D credit claim | Within 12 months of the end of the accounting period in which the expenditure was incurred. | Deadlines |
| Revenue assessment | Within 4 years after the end of the chargeable period in which the return is delivered; no time limit where the return was not full and true. | Revenue audits |
| Records | 6 years from the end of the accounting period, or from the date the return is delivered if later. | Documentation |
| Appeal | To the Tax Appeals Commission within 30 days after the date of the notice of assessment. | Reviews and audits |
Key rules to know
Notification and the 12 month limit interact. The notification requirement applies where the company has not made a claim under section 766C or section 766 in any of the 3 accounting periods immediately preceding the period for which the claim is made. Because the claim must be made within 12 months of the period end and the notice at least 90 days before the claim, the notice must in practice be given within 9 months of the period end.
Subcontracting is capped and must be notified. Expenditure on R&D activities carried on by an unconnected person on behalf of the company qualifies up to the greater of 15 percent of the company's own qualifying expenditure and €100,000, provided the person does not also claim. A company that subcontracts R&D to an unconnected person must notify that person in writing that it is claiming the credit.
Grants and overheads come out. Expenditure met directly or indirectly by grant assistance from the State, an EU institution or any other state is not qualifying expenditure. General overheads such as rent, rates, insurance and administration are excluded. Staff costs are apportioned according to the proportion of time spent on qualifying R&D activities, supported by records such as timesheets.
Location and instalments. Expenditure qualifies where the R&D activities are carried on within the State or another EEA state, and the expenditure is not relieved against tax in another territory. The first instalment is the greater of €75,000 (€87,500 where the 35 percent rate applies) and 50 percent of the credit, the second is three fifths of the remainder and the third the balance, each offset against tax or repaid at the company's election.
Worked example
Illustrative example. Shannon Photonics Limited, a hypothetical loss-making company with an accounting period from 1 January to 31 December 2025, has never claimed. The practitioner files the pre-filing notification by 23 June 2026, more than 90 days before the Form CT1 due on 23 September 2026. Own expenditure on two projects that pass the science test is €600,000: staff costs of €500,000, materials of €60,000 and plant and machinery of €40,000 apportioned to R&D use. An unconnected Irish firm was paid €150,000 and a university €20,000 to carry on parts of the work.
| Step | Amount |
|---|---|
| Own qualifying expenditure | €600,000 |
| Unconnected subcontractor: greater of 15% of own qualifying expenditure of €600,000 (€90,000) and €100,000 | €100,000 of the €150,000 qualifies |
| University: greater of 5% of €600,000 (€30,000) and €100,000 | €20,000 qualifies in full |
| Qualifying expenditure | €720,000 |
| Credit at 30% | €216,000 |
| First instalment: greater of €75,000 and 50% of €216,000 | €108,000 |
| Second instalment: three fifths of the remaining €108,000 | €64,800 |
| Third instalment: balance | €43,200 |
With no corporation tax to pay, the practitioner elects repayment for the first instalment on the 2025 Form CT1 and claims and elects for the second and third in the 2026 and 2027 returns; a profitable company could instead elect offset for any instalment. The claim can be amended only until 31 December 2026.
Related country guide pages
Self-check questions
Answer each question, then open it to compare.
A client with an accounting period ending 31 December 2025 last claimed the credit for 2021. Must it notify Revenue before claiming, and by when in practice?
Your client has own qualifying expenditure of €400,000 and pays an unconnected Irish engineering firm €120,000 to carry on part of the R&D. How much of the subcontracted cost qualifies?
A credit of €200,000 is claimed for a period commencing in 2025 and ending before 31 December 2026, with repayment elected. What are the three instalments?
Revenue writes to say it intends to consult an expert on the science test. What should the practitioner do before the meeting?
Before a Level 2 audit begins, the practitioner finds that €30,000 of general overheads were included in a filed claim. What is the right course?
Official sources
- Research and Development (R&D) Corporation Tax creditRevenue Commissioners
- Tax and Duty Manual Part 29-02-03, Research and Development Corporation Tax creditRevenue Commissioners
- Taxes Consolidation Act 1997, section 766Irish Statute Book
- Taxes Consolidation Act 1997, section 766CIrish Statute Book
- Taxes Consolidation Act 1997 (Prescribed Research and Development Activities) Regulations 2004, S.I. No. 434 of 2004Irish Statute Book
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Educational content only, not tax advice. See the disclaimer.