How Long Can You Carry Forward the R&D Tax Credit?

The R&D credit carryforward period is 20 years, and the carryback is 1 year, under IRC section 39, the carryover rule for general business credits. Research credit can be earned years before a company owes enough income tax to use it, so how carryforwards are ordered, limited and eventually retired decides how much of a credit turns into tax savings. This guide covers the federal rules: the carryback and carryforward periods, the order in which credits are used, the section 38(c) limit that creates unused credit, ownership changes, what happens at expiration, and where carryforwards appear on Form 3800.

R&D credit carryback and carryforward rules at a glance

The periods count taxable years, not calendar years, and section 7701(a)(23) treats a return for part of a year as covering a taxable year, so a short tax year, such as one created by a change of year-end, uses one of the 20. The credit belongs to the year it arose, which the statute calls the unused credit year, and every date below runs from that year.

Where unused credit comes from: the section 38(c) limit

The research credit is added to the year’s other general business credits, and section 38(c) caps the total that can offset tax in one year. “Net income tax” in these formulas is regular tax plus alternative minimum tax, reduced by the credits in subparts A and B of the Code’s credit provisions, which include the personal credits and the foreign tax credit; “net regular tax liability” leaves out the minimum tax.

Two consequences follow. A company with no income tax, such as a startup still reporting losses, cannot use any of its credit, so all of it carries. And a corporation with more than $25,000 of net income tax keeps paying some tax while it has credits: at $210,000 of tax, 25% of the $185,000 above $25,000, or $46,250, stays payable, and the credit can reduce the bill only to that amount. Owners who receive the credit through a sole proprietorship, partnership or S corporation also face section 41(g), which limits the research credit to the tax on their share of that business’s taxable income, with the excess carried under section 39.

Which credits are used first

The Form 3800 instructions describe general business credits as used first in, first out. In any tax year the order is:

1. Carryforwards to that year, the earliest ones first.
2. The general business credit earned in that year.
3. Any carryback to that year from the following year.

Using the oldest credit first matters because it is the credit closest to its 20-year deadline. When several kinds of credit arise in the same year, section 38(d) uses them in the order section 38(b) lists them, and the Form 3800 instructions place the research credit after the investment credit, the work opportunity credit and the biofuel producer credit of that year, ahead of the others.

Worked illustration: a credit used across four years

In 2025 there is no earlier year to carry back to, and the 2026 and 2027 credits find no room in the year before them, so everything moves forward. From 2027 each year spends its limit on the oldest credit first. All $450,000 is used by 2030, long before the deadlines: the 2025 credit could have been carried through 2045, the 2026 credit through 2046 and the 2027 credit through 2047. Had the company elected the section 280C reduced credit, each year’s credit would have been 79% of the amounts shown, with its section 174A research deduction left whole; the carryforward mechanics would be the same.

The one-year carryback

Section 39 sends an unused credit to the earliest year it can reach, which is the year before, and carries forward only what that year cannot absorb within its own section 38(c) limit. The statute has no election to skip the carryback, so the refund is worth claiming.

The Form 1139 instructions let a corporation other than an S corporation apply for a quick tentative refund within 12 months after the end of the year the unused credit arose, once that year’s return is filed; individuals use Form 1045. Either can instead file an amended return, and under section 6511(d)(4) a refund claim attributable to a credit carryback is timely until 3 years after the due date, including extensions, of the return for the year the credit arose.

The carryback did not change during the pandemic. The CARES Act (P.L. 116-136) added section 172(b)(1)(D), a 5-year carryback for net operating losses arising in tax years beginning in 2018 through 2020, but the amendment notes to section 39 list no change by that law.

When the carryforward runs out: section 196

Expired research credit is not simply lost. Section 196(a) allows a deduction equal to the credit never allowed, taken in the first tax year after the last year it could have been used under section 39. If the taxpayer dies or ceases to exist first, section 196(b) moves the deduction to the year of death or cessation. The research credit is on the list of qualified business credits in section 196(c)(4), with one exception: credit figured under the section 280C reduced credit election. The exception lines up with section 280C: claiming the full credit reduces the section 174A research deduction, while the reduced credit leaves that deduction whole.

Ownership changes: section 383

A corporation that changes hands can see the yearly use of its carryforwards sharply limited. Section 382(g) defines an ownership change as an increase of more than 50 percentage points in the stock owned by 5-percent shareholders over their lowest ownership during the testing period, generally the prior 3 years. New investors buying large stakes can add up to one. After the change, section 383(a) limits pre-change general business credit carryforwards, including research credit, to the tax on the taxable income that fits within the section 382 limitation, after pre-change losses have used what they need. The section 382 limitation is the value of the corporation’s stock just before the change times the long-term tax-exempt rate, and any unused part carries to the next year.

The regulation’s own example shows the scale. In Treas. Reg. 1.383-1(c)(6)(ii), a corporation with a December 31, 2021 ownership change has $100,000 of taxable income in 2022, a $25,000 section 382 limitation, a $12,000 pre-change net operating loss and a $50,000 pre-change general business credit carryforward. The loss uses $12,000 of the limitation, leaving $13,000. Tax falls from $18,480 to $15,750 when that $13,000 is deducted, so the section 383 credit limitation is $2,730: that year, only $2,730 of the $50,000 carryforward can be used. If the corporation does not continue the old business for 2 years after the change, section 382(c) generally sets the section 382 limitation at zero.

Pass-through owners and passive investors

Partnerships and S corporations do not carry research credit forward themselves. The entity computes the credit on Form 6765 and passes it to owners on Schedule K-1, and each owner uses, carries back or carries forward their share on their own return, subject to the section 41(g) limit above. The Form 3800 instructions apply that limit to carried credit as well: individual owners include the carryforward or carryback when figuring the research credit limit and then report only the allowable amount. An owner who does not materially participate in the business also faces section 469, which disallows passive activity credits beyond the tax on passive income; the disallowed credit is carried to the next year under section 469(b), and individuals track it on Form 8582-CR. An eligible small business’s research credit counts as a specified credit for an owner only if both the entity and the owner meet the $50 million gross receipts test.

Small companies: the payroll election instead of waiting

Some companies with no income tax to offset do not have to wait. A qualified small business, with under $5 million in gross receipts for the year and no gross receipts before the five-tax-year period ending with that year, can elect to apply up to $500,000 a year of its research credit against employer payroll taxes; the small business guide covers how that works. Two carryforward rules connect to it. For a qualified small business other than a partnership or S corporation, the elected amount cannot exceed the general business credit carryforward the year produces (section 41(h)(2)(C)), figured on a worksheet for Form 6765, line 35. And the amount elected leaves the income tax pool: the Form 3800 instructions say it cannot offset income tax or be carried back or forward, and the research credit carryforward is reduced by it.

How carryforwards appear on Form 3800 and Form 6765

Form 6765 figures each year’s credit; the carryforward itself lives on Form 3800. On the 2025 form, carryovers are reported in Part IV:

The Form 6765 instructions build the line 35 worksheet from Form 3800: the credits available, minus the credit allowed on line 38, minus any carryback amounts, equals the year’s general business credit carryforward. The Form 6765 and Form 8974 guide walks through the election lines around it.

Keeping a carryforward defensible

A credit carried forward is claimed again in every year it is used, and if its amount changes, Form 3800 asks for a statement of its history. Treas. Reg. 1.6001-1(e) requires records to be kept as long as their contents may become material, so the studies, payroll records and project files behind a 2025 credit can matter into the 2040s. If an examination or an amended return changes an earlier year’s credit, later years’ carryforwards can change with it, and the Form 3800 box for a changed or revised carryforward is checked. Companies that missed the credit in open years may be able to add it by amendment, and any part those years cannot use carries back and forward like any other credit; the amended return guide covers what the IRS requires, and Tax Planning is how BEG handles that recovery work. For what the credit is and how it is computed, see the R&D tax credit guide.

Sources: 26 U.S.C. 39; 26 U.S.C. 38; 26 U.S.C. 196; 26 U.S.C. 383; 26 U.S.C. 382; 26 U.S.C. 41; 26 U.S.C. 469; 26 U.S.C. 6511; 26 U.S.C. 172; 26 U.S.C. 7701(a)(23); IRS, Form 3800 (2025); IRS, Instructions for Form 3800 (2025); IRS, Instructions for Form 6765 (Rev. December 2025); IRS, Instructions for Form 1139 (Rev. December 2025); Treas. Reg. 1.383-1 (eCFR); Treas. Reg. 1.6001-1 (eCFR). Periods, limits, form lines and examples checked against these sources on September 25, 2026. This is general information, not tax advice for your situation. Tax services are provided by licensed tax professionals under a separate engagement agreement. BEG does not provide tax advice.