R&D Tax Credit in Ireland: What Companies Need to Know

The R&D tax credit in Ireland is a corporation tax relief that Revenue administers for companies carrying out qualifying research and development. Whether a company can claim depends on two things Revenue examines separately: whether the work meets the legal definition of R&D, and whether the money claimed was actually spent on that work. This guide walks through what Revenue's own manuals say about both tests, how a claim is made and what records matter, so finance teams in Dublin and elsewhere know what to check before filing. It describes guidance and does not replace advice from a tax adviser.

A note on figures. The credit rate, instalment amounts and several limits have changed over the years and are set out in Revenue's current manual and in legislation. We have deliberately not repeated rates here. Check the Revenue manual on the day you prepare a claim, and keep in mind that claims can be reviewed, as our guide to preparing for a Revenue audit or compliance intervention explains. Revenue's main manual on the credit (Tax and Duty Manual Part 29-02-03) shows a last-updated date of April 2026.

Who can claim and under which sections

According to Revenue's manual, the credit is governed by sections 766, 766A, 766B, 766C and 766D of the Taxes Consolidation Act 1997. The claimant must be a company within the charge to Irish tax. The manual also says the activity must be carried out in the EEA or the UK, and that for Irish tax-resident companies the expenditure must not receive a tax deduction under another territory's law. The company does not need to own the resulting intellectual property, and the work does not need to succeed. The manual explains that the Act requires the activity to seek an advance, not to achieve one.

If a company is claiming for the first time, or has not claimed in the previous three years, the manual says Revenue must be notified in advance through a pre-filing notification. Revenue publishes pre-filing forms for sections 766C and 766D on its R&D pages.

The five tests for a qualifying activity

Revenue's manual states that an activity qualifies only if it meets all five conditions. The expert-appointment manual (Part 29-02-05, last updated August 2025) repeats the same five questions as a checklist:

• Systematic, investigative or experimental: the work follows a planned approach rather than being ad hoc.
• A field of science or technology: social science activities are specifically outside the definition.
• Basic research, applied research or experimental development: the work must fall into at least one of these categories.
• Seeking scientific or technological advancement: measured against the overall knowledge available at the time, not against the company's own capability.
• Resolving scientific or technological uncertainty: commercial uncertainty about whether a product will sell is not enough.

What Revenue says generally does not qualify

The manual lists a number of situations that on their own do not meet the test. These include using science or technology in a product without advancing knowledge, buying rights or licences, solving technical problems with generally available knowledge, and established management methods such as Lean process improvement. Uncertainty that a competent professional could resolve from reasonably available knowledge does not count, and lack of in-house expertise or diligence does not create uncertainty.

For software, the manual says routine analysis, copying, upgrading or adapting existing software, and standard development with standard tools generally do not qualify. In agile projects, it expects staff and other costs to be apportioned between qualifying and non-qualifying work on the basis of effort. If your team builds software in Dublin, that apportionment is worth planning for from the start of a project.

The accounting test: what spending counts

The second test is about the money. The manual says expenditure claimed as spent on qualifying R&D must be correctly classified, and it lists categories that are not eligible, including recruitment, insurance, travel, entertainment and bank charges, and the overheads of employment such as HR and payroll. Grant-funded expenditure and capital expenditure that qualifies for another allowance are also dealt with separately. Subcontracting is subject to a limit in the manual, and group, outsourcing and key-employee rules each have their own sections. Because these rules are detailed and change, we leave out the figures. Read the relevant sections of the manual for the accounting period you are claiming.

How a claim is made

The manual says claims are made on the Form CT1 through ROS, within 12 months after the end of the accounting period in which the expenditure was incurred. It also explains that the credit is paid or offset in three annual instalments, with the company specifying on the CT1 whether each instalment is offset against tax or paid by Revenue. The exact calculation of the instalments depends on the section and the period, so use the manual rather than a summary.

Revenue also published operational guidance (Part 29-02-03A, created August 2023) for 2022 claims, which required a separate specified return spreadsheet submitted through MyEnquiries. That guidance says claims for 2023 and later years use questions on the Form CT1 itself. Revenue's R&D how-to video page (published 18 July 2025) walks through the R&D panels of the Form CT1 for 2024, including carried-forward amounts and group relief. For the 2022 specified return, the guidance says no R&D supporting documents need to be sent with it, but that Revenue may ask for them later.

Records: the science test and the paper trail

Documentation is where claims are most exposed. The manual says work should follow a planned, logical sequence and that the claimant must be able to show the activities carried out, not just the outcomes. It expects each project to be documented with dated records of the original goals, progress, methods and conclusions, and it expects records to be contemporaneous. If one path failed and another was taken, the reasons should be recorded. Claims lacking adequate documentation may be disallowed in whole or in part, and the manual says that where only one project lacks documentation Revenue will disallow only that project's portion.

A practical approach: ask the technical lead of each project to keep a short dated log of the technical uncertainty at the start, the experiments tried, and what was learned, and have finance keep time and cost records that map to the same project names. Our suggestion is to review this at the end of every quarter rather than at year end.

Revenue review, experts and clawback

Revenue's manual says a claim may be examined by reference to two criteria: a science test and an accounting test. Where there is doubt on the science, the expert manual says an independent expert may be appointed by Revenue, with the appointment letter sent by an authorised officer. The company is told who the expert is and may object if there is a conflict of interest or if the expert's expertise does not suit its R&D activities. The company has a right of reply before the report is finalised. The manual also notes that experts may have to give evidence before the Tax Appeals Commission or a court.

Revenue's separate clawback manual (Part 29-02-06, last updated November 2022) covers clawback of credits that were not properly due, with related interest and penalties. Check the current version before relying on it. If a claim is selected for a compliance intervention, it helps to know how Revenue approaches these reviews; see our audit guide linked in the introduction. Companies that claim the credit should also keep their tax payments on schedule; our article on preliminary tax rules and deadlines covers that side.

Skills for the finance team

An R&D claim sits between engineers and accountants, and mistakes usually come from poor hand-offs. Finance staff who understand how the five tests are applied can ask better questions of project teams. For ongoing professional development in this area, see our overview of CPD training for finance professionals in Dublin.

Learnsignal's offices are off Baggot Street in Dublin, and we offer in-person training from there. For current details, see our CPD pages.

Frequently asked questions

Does a project have to succeed to qualify?

No. Revenue's manual says the work does not need to succeed. The activity must seek scientific or technological advancement and involve resolving uncertainty, and activities that seek an advance but fail can still qualify.

Do we need to send technical documents with the return?

The operational guidance Revenue published for 2022 claims says no supporting documents need to be sent with the return, but Revenue may request them later. Keep them in a form you can produce.

Is there a time limit for claiming?

Revenue's manual states a limit of 12 months after the end of the accounting period in which the expenditure was incurred. Confirm the current rule in the manual before filing.

Can Revenue challenge the science of a claim?

Yes. Revenue's manuals describe a science test, and an independent expert may be appointed by Revenue. The company may object if there is a conflict of interest or if the expert's expertise does not suit its R&D activities.

Where do I find current rates?

In Revenue's Tax and Duty Manual Part 29-02-03 and in the legislation. We have not repeated rates because they differ by accounting period and may change.

This article is general information based on Revenue guidance and is not tax advice. Check the current manuals on revenue.ie before preparing a claim.