Claiming Past R&D Credits: Six Questions About the IRS Refund Claim Rules

TL;DR

• You can generally still claim R&D credits for prior open tax years by amending, but the IRS now requires specific information up front for the refund claim to be valid at all.
• Through January 10, 2027, the IRS gives you 45 days to fix an incomplete claim. After that window closes, a deficient claim can simply be rejected, with no opportunity to cure and no path to Appeals.
• The practical takeaway: a lookback claim is still very much worth pursuing, but the era of filing a thin amended return and sorting out details later is over.

The rules changed quietly, and the grace period is ending

Many owners and CFOs first hear about the R&D tax credit years after they started doing qualifying work. The natural next question is whether those past years are recoverable. Often they are. But the IRS has spent the last several years tightening what a refund claim involving the credit must contain, and the transition relief that softened those rules has an end date. Here are the questions we hear most, answered from the IRS's own guidance.

1. Can we still claim the credit for years we already filed?

Generally, yes. If your company performed qualifying research in a prior year and never claimed the credit under IRC Section 41, you may be able to file an amended return claiming a refund, as long as the year is still open under the statute of limitations. That window is generally the later of three years from when the return was filed or two years from when the tax was paid, though the specifics depend on your facts, so confirm the open years before assuming anything.

2. What has to be in the claim for the IRS to even consider it?

This is where the rules changed. For a refund claim involving the research credit to be valid, the IRS requires specific information at the time of filing, per its research credit refund claim FAQ. As of June 18, 2024, three items are required: identify every business component the claim relates to for that year; for each business component, identify all research activities performed; and provide the total qualified wage, supply, and contract research expenses for the claim year, which can be done on Form 6765. The IRS previously also required the names of the individuals who performed each activity and what each sought to discover. That requirement is waived at filing, but the IRS can still request it if the claim is examined, so the underlying detail needs to exist.

3. What is the 45-day perfection period, and why does January 10, 2027 matter?

During the current transition period, if the IRS determines your claim is missing required information, it mails a letter identifying what is missing and gives you 45 days to perfect the claim. That transition relief runs through January 10, 2027. The IRS has extended it before and could again, but nothing requires it to. If the relief lapses as scheduled, a claim filed with incomplete information can be treated as invalid without any opportunity to fix it.

4. What happens if a claim is rejected as deficient?

The entire refund claim is rejected, not just the incomplete portion. And unlike claims disallowed on timeliness grounds, claims rejected as deficient are not eligible for review by the IRS Independent Office of Appeals. The recourse at that point is narrow, which is exactly why the claim needs to be complete the first time.

5. How long does the IRS take on these claims?

The IRS has stated it attempts to make determinations on research credit refund claims within six months of receipt. Treat that as a goal rather than a promise, and plan cash flow accordingly.

6. Does any of this affect a current-year claim?

The validity rules above apply to refund claims, meaning credits claimed through amended returns. Claiming the credit on your originally filed return does not trigger the refund claim requirements, though reporting expectations are rising there too: the redesigned Form 6765 is phasing in more detailed business-component reporting for most filers. The direction of travel is the same everywhere: the IRS wants claims that connect specific research activities to specific expenses, documented at the project level. Companies that build the claim that way from the start, as described in Treasury Regulation 1.41-4, have little to fear from any of it.

What this means for a growing company

None of this is a reason to leave prior-year credits unclaimed. It is a reason to claim them properly. For a company in the $3M to $15M range, the work of identifying business components, mapping activities to them, and tying expenses to both is very manageable with the right help, and most of that effort sits with the provider rather than your team. Strata builds lookback claims at the business-component level, works directly with your CPA, and starts with a $0 initial assessment, so you can find out what your open years may hold before committing to anything. Contact us to take a look.

This post is for informational purposes only and does not constitute tax or legal advice. Consult a qualified tax professional regarding your specific circumstances.