§41(a): the credit and its three components
Subsection (a) sets the credit as the sum of three amounts. The one almost every claim rests on is §41(a)(1): 20% of the excess of the year’s qualified research expenses over a base amount. §41(a)(2) adds 20% of basic research payments determined under subsection (e), and §41(a)(3) adds 20% of amounts paid to an energy research consortium for energy research.
The credit is “for purposes of section 38”, which makes it part of the general business credit. It reduces income tax subject to the §38(c) limitation, and anything unused carries back one year and forward twenty under §39. It is a credit, not a deduction, so a dollar of credit is a dollar less tax.
Everything else in §41 defines the inputs to (a)(1) or changes who gets the credit and how it is used.
§41(b): qualified research expenses, in-house and contract
QREs are amounts paid or incurred in carrying on a trade or business, in two families: in-house research expenses and contract research expenses.
In-house research expenses, §41(b)(2)
- Wages for qualified services: engaging in qualified research, or directly supervising or directly supporting it. Wages means §3401(a) wages, excluding amounts used for the work opportunity credit. If substantially all of a person’s services qualify, all of their wages count; §1.41-2(d)(2) sets that line at 80%.
- Supplies used in the conduct of qualified research: tangible property other than land, land improvements and depreciable property. Ordinary utilities are general and administrative; only extraordinary research-driven utility costs can count.
- Computer use: amounts paid to another person for the right to use computers in qualified research. Under §1.41-2(b)(4) the computer must be owned and operated by someone else, off your premises, and you must not be its primary user.
Contract research expenses, §41(b)(3)
- 65% of amounts paid to a non-employee for qualified research on your behalf. 75% for payments to a qualified research consortium, and 100% for energy research paid to an eligible small business, a university or a federal laboratory.
- Under §1.41-2(e) the agreement must be entered into before the research is performed, must provide for research on your behalf, and must leave you bearing the expense even if the research fails. Payment contingent on success is payment for a result, not for research.
- “On behalf of” means you have a right to the results, even if not exclusive.
Who counts as a direct supervisor or direct support
§1.41-2(c) limits direct supervision to first-line management, not the manager those supervisors report to. Direct support includes a lab worker cleaning research equipment or a machinist building an experimental part; it excludes payroll, research-cost accounting and general administration. §41(b)(4) lets a start-up count in-house expenses before it has a trade or business, if it intends to use the results in one. More in the QRE guide.
§41(c): the base amount, and the ASC in (c)(4)
The base is the slice of research spending the statute treats as ordinary. Only spending above it earns the credit.
Under §41(c)(1) the base amount is the fixed-base percentage multiplied by average annual gross receipts for the four taxable years before the credit year. §41(c)(2) floors it at 50% of current-year QREs, which is why the Regular credit can never exceed 10% of QREs.
The fixed-base percentage in §41(c)(3) is QREs over gross receipts for tax years beginning after 1983 and before 1989. A start-up uses 3% for its first five taxable years with QREs (beginning after 1993), then a phased-in ratio from later years. The cap is 16%. Under (c)(5), base-period QREs are measured consistently with the credit year, even for closed years.
§41(c)(4) is the alternative simplified credit: 14% of QREs above 50% of the average QREs for the three preceding years, or 6% of current QREs if there were no QREs in any one of those three years. The election applies to the year made and all later years unless revoked with IRS consent. Calculation methods works both through with numbers.
What the regulations add
- Gross receipts, §1.41-3(c). All receipts under your accounting method, excluding returns and allowances, capital asset sales, loan repayments, non-ordinary-course sales, collected sales taxes, and receipts from years before you first earned over $25,000 of non-investment receipts.
- Short years. A short credit year’s (c)(1) base is multiplied by months over 12 (§1.41-3(b)); the ASC average is multiplied by days over 365 (§1.41-9(c)(3)).
- ASC elections, §1.41-9(b). Made on Form 6765 with a timely original return. An amended-return election is allowed only if no §41(a)(1) credit was claimed for that year and the year is still open. Revocation happens on an original return, never an amended one.
The regulations still use older numbering: §1.41-9 calls the ASC “§41(c)(5)”. It became (c)(4) when P.L. 115-141 (2018) struck the old alternative incremental credit paragraph.
§41(d): qualified research, the four-part test and its exclusions
Section 41 qualified research activities are defined here. Every test is applied separately to each business component.
§41(d)(1) requires research (A) whose expenditures are treated as domestic research or experimental expenditures under §174A; (B) undertaken to discover information that is technological in nature and intended to be useful in developing a new or improved business component; and (C) where substantially all of the activities are elements of a process of experimentation for a qualified purpose. That is the four-part test.
A business component under (d)(2) is a product, process, computer software, technique, formula or invention held for sale, lease or license, or used in your trade or business. A production process is a separate component from the product it makes. Under (d)(3), the purpose must relate to function, performance, reliability or quality, never style, taste, cosmetic or seasonal design.
Treas. Reg. §1.41-4(a) fills in each part. Uncertainty exists if available information does not establish the capability, method or appropriate design. You need not advance the field’s common knowledge or succeed. The experimentation must rely on the physical or biological sciences, engineering or computer science, and evaluate alternatives by modeling, simulation or systematic trial and error. “Substantially all” means 80% or more of the activities, measured on cost or another consistent basis.
The shrinking-back rule in §1.41-4(b)(2) applies the tests first to the whole component, then to successively smaller subsets of its elements, until a subset qualifies or the most basic element fails. It rescues qualifying work inside a larger project; it is never a reason to exclude activity.
Internal-use software, §1.41-4(c)(6)
Software developed primarily for your own general and administrative functions (financial management, human resources, support services) must pass a high threshold of innovation test on top of the four-part test: it must be innovative, involve significant economic risk from technical uncertainty, and not be commercially available for your purpose without modifications that would themselves meet the first two requirements.
Software sold, leased or licensed to others, or built so third parties can interact with your systems, is not internal-use. Dual-function software is presumed internal-use, with a third-party subset carve-out and a 25% safe harbor. Read more on internal-use software and the high threshold of innovation.
Records, §1.41-4(d): keep records in sufficiently usable form and detail to substantiate that the expenses claimed are eligible. See our documentation guide.
The eight §41(d)(4) exclusions
| §41(d)(4) | Excluded activity | In practice |
|---|---|---|
| (A) | Research after commercial production | Work after the component is ready for commercial sale or use. Pre-production clinical testing of a pharmaceutical is not treated as post-production (Treas. Reg. §1.41-4(c)(2)(iv)). |
| (B) | Adaptation of an existing business component | Tailoring something that already exists to one customer’s requirement, as opposed to resolving new technical uncertainty. |
| (C) | Duplication | Reproducing an existing component from a physical examination, plans, blueprints, specifications or public information. |
| (D) | Surveys, studies and similar | Efficiency surveys, management techniques, market research and advertising, routine data collection, routine quality-control testing. |
| (E) | Internal-use software | Excluded except as the regulations allow. Treas. Reg. §1.41-4(c)(6) lets it qualify if it also passes a high threshold of innovation test. |
| (F) | Foreign research | Research outside the United States, Puerto Rico or a U.S. possession. |
| (G) | Social sciences, arts, humanities | Research in those fields, however rigorous. |
| (H) | Funded research | Research to the extent funded by a grant, contract or another person. Contract terms on payment and rights to results decide it. |
§41(e): basic research payments
Basic research is original investigation to advance scientific knowledge without a specific commercial objective, performed in the United States. A basic research payment is cash a corporation pays under a written agreement to a qualified organization, such as a university or a qualifying scientific research organization.
The (a)(2) credit applies to payments above a qualified organization base period amount, the sum of a minimum basic research amount and a maintenance-of-effort amount tied to past university giving. The portion at or below that base is not lost; it is treated as contract research under (a)(1).
§41(f): special rules, including controlled groups
Aggregation, allocation, acquisitions and short years. Most multi-entity mistakes start here.
One group, one credit
Under §41(f)(1) all members of a controlled group of corporations, and all trades or businesses under common control, are treated as a single taxpayer. For this purpose §41(f)(5) uses a more than 50% ownership test rather than the usual 80%. §1.41-6 computes the group credit on an aggregate basis, requires every member to use the same method, and allocates the credit in proportion to each member’s share of group QREs, basic research payments and energy consortium amounts.
Acquisitions, dispositions and short years
§41(f)(3) moves a predecessor’s QREs and gross receipts with an acquired business, so the base keeps tracking the same research. §41(f)(4) covers short years, §41(f)(2) allocates the credit among partners and beneficiaries, and §41(f)(6) defines the energy research consortium behind (a)(3).
§41(g): the pass-through limitation
For an individual who owns part of an unincorporated business, is a partner, is a beneficiary of an estate or trust, or is an S corporation shareholder, the credit from that interest cannot exceed the tax attributable to the taxable income allocable to it. Any excess carries to other years under §39, with this limitation used in place of §38(c).
An owner with little tax on the business income may be unable to use their share this year, one reason the §280C(c) election and the payroll election deserve modeling for pass-throughs.
§41(h): the payroll tax election for small businesses
A qualified small business, one with gross receipts under $5 million for the year and no gross receipts in any year before the five-year period ending with it, may elect to apply part of its credit against employer payroll tax under §3111(f). The cap is $250,000, plus another $250,000 for taxable years beginning after 2022. A business may elect for at most five years, and any business other than a partnership or S corporation (for example a C corporation or a sole proprietor) can elect no more than the credit that would otherwise carry forward from the year.
The election is made on or before the return’s due date including extensions, and partnerships and S corporations make it at the entity level. The mechanics are in our payroll tax offset guide and the Form 8974 walkthrough.
The regulations that do the heavy lifting
The statute sets the frame. Examiners and courts work from the regulations, so read them together.
| Regulation | Covers | Rules worth knowing |
|---|---|---|
| §1.41-2 | Qualified research expenses | First-line supervision only; direct support examples; the 80% "substantially all" wage rule; off-premises computer rental; contract research agreements. |
| §1.41-3 | Base amount and gross receipts | New taxpayers; short years (months over 12); what gross receipts include and exclude; consistency between base years and the credit year. |
| §1.41-4 | Qualified research | Uncertainty; technological in nature; process of experimentation; the 80% substantially-all test; shrinking-back; exclusions; internal-use software in (c)(6); recordkeeping in (d). |
| §1.41-6 | Controlled groups | Group credit computed as one taxpayer, one method for all members, allocation in proportion to each member’s share of group QREs. |
| §1.41-9 | Alternative simplified credit | Election on Form 6765 with a timely original return; limited amended-return elections; revocation only on an original return; short years (days over 365). |
What changed in §41 recently
Three laws account for most of the text you read today.
| Law | Change | Effective |
|---|---|---|
| P.L. 114-113 (PATH Act, 2015) | Made the credit permanent and added the §41(h) payroll tax election for qualified small businesses. | Permanence: amounts paid or incurred after 2014. Payroll election: taxable years beginning after 2015 |
| P.L. 117-169 (Inflation Reduction Act, 2022) | Added a second $250,000 to the §41(h) election cap, applied against employer Medicare tax through §3111(f). | Taxable years beginning after December 31, 2022 |
| P.L. 119-21 (One Big Beautiful Bill Act, 2025) | §41(d)(1)(A) now ties qualified research to domestic research or experimental expenditures under new §174A. §280C(c)(1) was also rewritten. | Amounts paid or incurred in taxable years beginning after December 31, 2024 |
The 2025 law matters most for how the credit interacts with deductions. Domestic research costs are deductible again under §174A, and §280C(c) now reduces that deduction by the credit unless you elect the reduced credit. See §174A vs. §41, the §174A expensing guide, and R&D credit changes for 2026.
IRC §41 questions we get most
What is IRC Section 41?
What is Treas. Reg. §1.41-4?
What is Treas. Reg. §1.41-2?
Is the §41 credit permanent?
How does §174A relate to §41 after the 2025 law?
Can a company with no revenue use §41?
For the plain-English version of subsection (d), read the four-part test in plain English; for how contract terms decide §41(d)(4)(H), read funded research and your contracts.
Primary sources
The statute and regulations this guide summarizes, as retrieved September 28, 2026.
- 26 U.S.C. §41 - Credit for increasing research activities (Cornell LII)
- 26 U.S.C. §41 (Office of the Law Revision Counsel, uscode.house.gov)
- Treas. Reg. §1.41-2 - Qualified research expenses (Cornell LII)
- Treas. Reg. §1.41-3 - Base amount (Cornell LII)
- Treas. Reg. §1.41-4 - Qualified research (Cornell LII)
- Treas. Reg. §1.41-6 - Controlled groups (Cornell LII)
- Treas. Reg. §1.41-9 - Alternative simplified credit (Cornell LII)
- 26 U.S.C. §39 - Carryback and carryforward (Cornell LII)
Tax law and regulations change, and paragraph numbering in §41(c) has moved with past legislation. Verify current rules with a qualified professional before acting.