An expected federal research credit can reduce required estimated tax payments, because the corporate rules in section 6655 and the individual rules in section 6654 both figure installments on tax after the credits allowed under part IV of subchapter A of chapter 1, which include the general business credit. The reduction is limited to the credit the taxpayer can use for the year under section 38(c). If the credit on the return comes in lower than the estimate, installments based on the current year’s tax can be underpaid and bear an addition to tax unless a prior-year safe harbor covers them.
Why the Credit Reduces Required Installments
“Tax” is measured after credits. For corporations, section 6655(g)(1) defines tax as the income tax under section 11 (or subchapter L) and the other taxes it lists, minus “the credits against tax provided by part IV of subchapter A of chapter 1.” The research credit is part of the general business credit in section 38, which sits in part IV, so a credit the corporation will use for the year lowers its tax for this purpose.
The required annual payment uses that figure. A corporation’s required annual payment is the lesser of 100 percent of the tax shown on its return for the year or 100 percent of the tax shown on its return for the preceding year, if that year was 12 months and the return showed a liability (section 6655(d)(1)(B)). Each of the four installments is generally 25 percent of that amount. An expected credit lowers the current-year measure; the prior-year measure reflects the credits on the prior-year return.
The individual rules work the same way. Section 6654(f) measures an individual’s tax as the taxes under chapters 1, 2 and 2A, minus the part IV credits other than the credit for withholding under section 31. The required annual payment is the lesser of 90 percent of the current year’s tax or, if the prior year was 12 months and a return was filed for it, 100 percent of the prior year’s tax, which becomes 110 percent if the prior year’s adjusted gross income exceeded $150,000, or $75,000 for a married individual filing separately (section 6654(d)(1)).
Corporate Installments Under Section 6655
Four installments, set by month of the tax year. Installments are generally due on the 15th day of the 4th, 6th, 9th and 12th months of the corporation’s tax year (Instructions for Form 2220 (2025); section 6655(c) and (i)).
Three ways to figure an installment. The regular method uses 25 percent of the required annual payment. A corporation can instead use the annualized income installment method or, if it meets the 70 percent base period test, the adjusted seasonal installment method (section 6655(e); Form 2220, Schedule A). Schedule A takes the credits for the months in each period without annualizing them, although income and deduction items used to figure a credit are annualized, so the research credit for a partial-year period needs its own computation with your tax adviser.
The large corporation limit. A large corporation, one with taxable income of $1 million or more in any of the three preceding tax years, with members of a controlled group sharing the $1 million, can use the prior-year measure only for its first installment, and any reduction from doing so is recaptured in the next installment (section 6655(d)(2) and (g)(2)). After the first installment, its installments rest on current-year tax, so its estimate of the research credit directly affects what it pays.
| Rule | Corporations (section 6655) | Individuals (section 6654) |
| Installments | 15th day of months 4, 6, 9 and 12 | April 15, June 15, Sept. 15, Jan. 15 (calendar year) |
| Current-year measure | 100% of tax for the year | 90% of tax for the year |
| Prior-year measure | 100% of prior-year tax | 100%, or 110% if prior AGI over $150,000 |
| Prior-year limit | 12-month prior year with tax shown; large corporations: first installment only | 12-month prior year with a return filed |
| Other methods | Annualized; adjusted seasonal | Annualized |
| No addition if tax is under | $500 | $1,000 after withholding |
Owners of Pass-Through Entities Under Section 6654
The credit reaches the owner’s own estimate. A partnership or S corporation passes its research credit through to its owners, who claim it against their own tax. Because section 6654(f) subtracts part IV credits, an owner’s expected share reduces the tax used for the owner’s installments, subject to the section 38(c) limit and owner-level limits. Our article on the R&D credit for S corporations and partnerships covers those limits.
The information may come late. An owner often learns the amount of the credit only when the Schedule K-1 arrives. Basing installments on the prior year’s tax, at 100 or 110 percent, avoids depending on an estimate of the current year’s credit.
Limits, Underpayment Risk and the Payroll Election
Only usable credit reduces tax. Section 38(c) caps how much general business credit, including the research credit, can offset tax in a year, and credit above the cap does not reduce that year’s tax. Our article on the general business credit limitation explains the computation. Unless the reduced credit is elected under section 280C(c), the credit also reduces the section 174A deduction, which raises taxable income; an estimate should reflect both effects.
If the credit comes in lower. The corporate addition is figured separately for each installment at the underpayment rate under section 6621, generally from the installment’s due date until the underpayment is paid or, if earlier, the 15th day of the 4th month after the close of the tax year. A corporation can owe an addition for an earlier installment even if it paid enough later, and even if it is due a refund when it files (Instructions for Form 2220 (2025)).
An illustration. The figures are hypothetical. A calendar-year C corporation that is not a large corporation expects $400,000 of tax before credits and a $100,000 research credit, the section 38(c) limit does not bind, and its prior-year tax was $350,000. Section 280C and state tax are ignored.
| Outcome | Tax for the year | Required annual payment | Each installment |
| Credit as estimated | $300,000 | $300,000 | $75,000 |
| Credit comes in at $60,000 | $340,000 | $340,000 | $85,000 |
If the corporation paid $75,000 per installment and the credit came in at $60,000, each installment would be $10,000 short. Paying $87,500 per installment, 25 percent of the prior year’s $350,000, would have covered either outcome, but a large corporation could rely on that measure only for its first installment.
The payroll election does not reduce income tax estimates. A qualified small business can elect under section 41(h) to apply up to $500,000 of research credit a year against the employer share of Social Security tax and then Medicare tax. The elected amount is applied against payroll taxes on Form 8974 rather than against income tax, so it does not lower the tax used for income tax installments. Our Form 8974 guide covers the quarterly mechanics.
Each of these decisions starts from an estimate of the credit, and the installment computation is one to work through with your tax adviser. You can request a no-cost analysis from CSSI Services or read about our R&D tax credit services.
Frequently Asked Questions
Can a company lower its estimated tax payments for an expected R&D credit?
Generally yes. Corporate and individual installments are figured on tax after part IV credits, which include the research credit, so a credit the taxpayer expects to use for the year reduces the current-year measure. The reduction is limited to credit usable under section 38(c), and an overestimate can lead to an underpayment addition.
Can a large corporation rely on last year’s tax instead?
Only for its first required installment. Any reduction from using the prior year’s tax for that installment is recaptured in the next one, and later installments rest on current-year tax.
What happens if the credit turns out smaller than estimated?
Installments based on current-year tax may be underpaid, and the addition is figured separately for each installment from its due date. A taxpayer that is not a large corporation and paid installments based on the prior year’s tax on time is generally covered where the prior-year measure is available.
Does the payroll tax election reduce estimated income tax payments?
No. The amount a qualified small business elects is applied against the employer share of Social Security and Medicare taxes on Form 8974, not against income tax, so it does not reduce the tax used for income tax installments.
Do S corporation shareholders and partners get the same benefit?
Their share of the credit reduces the tax used for their own installments under section 6654, subject to the section 38(c) limit and owner-level limits. Because the share is often known only when the Schedule K-1 arrives, an owner may base installments on the prior year’s tax instead.
This article provides general information about federal tax rules and is not tax advice. Speak with your tax adviser about your specific circumstances.
