General Business Credit: How Tax Credits Work Together and the Carryback and Carryforward Rules Under IRC 38

By Yarik Yarosh, CPA ·September 5, 2026 ·Updated October 19, 2026 ·8 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

Business tax credits are dollar-for-dollar reductions in tax liability, making them far more valuable than deductions (which only reduce taxable income). A $10,000 tax credit saves $10,000 in tax, while a $10,000 deduction saves only $3,700 (at 37%) or $2,100 (at 21% for corporations). Under IRC 38, the general business credit combines all qualifying business credits into a single calculation with a unified limitation and carryover rules. The limitation prevents a business from using credits to reduce its tax liability below a floor (generally the tentative minimum tax), which means businesses with large credit amounts relative to their taxable income may not be able to use all of their credits in the current year. However, the 1-year carryback and 20-year carryforward rules give unused credits up to 21 other years to be used before they expire. The interaction between multiple credits, the ordering rules, and the limitation calculation make Form 3800 one of the most complex forms in the tax code, but the planning opportunity is substantial: businesses that understand how to time their activities (hiring, R&D spending, equipment purchases, energy improvements) to maximize credit utilization can save tens of thousands of dollars in tax every year.

✓Key takeaway

Major business tax credits included in the general business credit (IRC 38):

Credit	IRC Section	Maximum Amount	Common Claimants
R&D Credit	IRC 41	No dollar cap; 20% of qualified expenses above base	Tech, manufacturing, engineering, pharma
Work Opportunity Tax Credit (WOTC)	IRC 51	Up to $9,600 per qualifying employee; only for hires who began work before 2026 unless Congress extends it	Hospitality, retail, staffing
Small Employer Health Insurance Credit	IRC 45R	50% of premiums paid (35% for tax-exempt)	Small employers (fewer than 25 FTEs, average wages under $67,000 for 2025)
Disabled Access Credit	IRC 44	$5,000 max ($250 floor)	Small businesses (≤$1M revenue or ≤30 employees)
Employer-Provided Childcare Credit	IRC 45F	For amounts paid after 2025: 40% of facility costs (50% for an eligible small business) + 10% of resource/referral costs, up to $500,000 ($600,000 small business); $150,000 and 25% before 2026	Employers providing childcare
Low-Income Housing Credit	IRC 42	9% or 4% of qualified basis (10-year credit period)	Real estate developers/investors
Investment Tax Credit (ITC)	IRC 46	6% base or 30% with prevailing wage and apprenticeship, plus bonus points for domestic content, energy communities and some low-income projects (IRC 48, 48E); wind and solar face a placed-in-service cutoff after 2027	Solar, wind, energy storage
Small Business Health Care Credit	IRC 45R	Up to 50% of premiums	Employers with fewer than 25 FTEs
Paid Family and Medical Leave Credit	IRC 45S	12.5-25% of wages paid during leave	Employers with written leave policies
Employer Social Security Credit (Tips)	IRC 45B	Employer FICA on tips above the amount needed to reach the federal minimum wage (the January 1, 2007 rate for food and beverage businesses)	Restaurants, hospitality

General business credit limitation formula:

Step	Calculation
1. Net income tax	Regular tax + AMT - nonrefundable personal credits
2. Tentative minimum tax	Computed per IRC 55 (most corporations: $0 post-TCJA)
3. Limitation floor	Greater of: tentative minimum tax OR 25% of (net regular tax - $25,000)
4. General business credit allowed	Net income tax - limitation floor

How do business tax credits work together?

Hypothetical example

Round numbers. A manufacturing S-Corp has the following tax situation:

Income and tax:

Item	Amount
Taxable income (pass-through to owner)	$500,000
Federal tax before credits (flat 37%, for round numbers)	$185,000
Tentative minimum tax	$0 (assumed only to keep the math simple; see the note below the limitation)

Credits earned:

Credit	Amount
R&D Credit (IRC 41)	$40,000
WOTC (3 qualifying hires)	$7,200
Disabled Access Credit (ramp installation)	$3,500
Energy Investment Tax Credit (solar panels on facility)	$25,000
Total credits	$75,700

General business credit limitation:

Step	Calculation	Amount
Net income tax	$185,000
Tentative minimum tax	$0
25% of (net regular tax - $25,000)	25% x ($185,000 - $25,000) = $40,000
Limitation floor	Greater of $0 or $40,000	$40,000
Maximum general business credit	$185,000 - $40,000	$145,000

On these assumptions, all $75,700 of credits can be used (they are below the $145,000 limitation). With a real tentative minimum tax, only the specified credits in IRC 38(c)(4) (they include WOTC, the section 48 energy credit and an eligible small business’s R&D credit) can still reach the 25% floor; others, such as the disabled access credit, stop at the tentative minimum tax.

Tax after credits:

Item	Amount
Tax before credits	$185,000
General business credit	($75,700)
Tax after credits	$109,300
Effective tax rate	21.9% (vs. 37% marginal rate)

Scenario with credits exceeding the limitation: What if the business had $300,000 in credits but only $185,000 in tax?

Item	Amount
Total credits earned	$300,000
Maximum credit allowed (from limitation)	$145,000
Credits used in current year	$145,000
Excess credits	$155,000

Carryover rules:

Rule	Details
Carryback	1 year (can amend the prior year’s return to use the excess); 3 years for the clean energy credits listed in IRC 6417(b), such as the energy investment credit
Carryforward	20 years
Ordering	Carryforwards first (oldest first), then current-year credits, then carrybacks
Expiration	Credits expire after the 20-year carryforward period

Credit ordering (which credits are used first): When multiple credits are available, they’re applied in the order listed in IRC 38(b). Generally:

Priority	Credits
1st	Investment credit, WOTC, alcohol fuels credit
2nd	R&D credit
3rd	Low-income housing credit
4th	Enhanced oil recovery credit
5th	Disabled access credit
6th	Renewable electricity production credit
Last	All other credits

This ordering is fixed by statute (IRC 38(d)), not chosen by you; it matters when only part of your credits can be used, because it decides which credits are treated as used and which carry over.

Refundable vs. nonrefundable credits:

Type	Tax Treatment	Examples
Nonrefundable	Can reduce tax only down to the IRC 38(c) limit (no refund for excess; it carries back or forward)	Most general business credits
Refundable or payroll offset	Can produce a refund or offset another tax even if no income tax is owed	R&D credit for small businesses (IRC 41(h): up to $500,000 offset against payroll tax, not a refund); elective payment of clean energy credits for tax-exempt entities (IRC 6417)

Small business R&D credit against payroll tax (IRC 41(h)):

Requirement	Details
Qualifying small business	Gross receipts < $5 million AND no gross receipts for any tax year before the 5-year period ending with the current year
Maximum offset	$500,000 per year: up to $250,000 against the employer Social Security tax, the rest against the employer Medicare tax
Election	Must elect on Form 6765
Useful for	Startups with no taxable income but qualifying R&D expenses

Planning strategies for maximizing credit utilization:

Strategy	How It Works
Time R&D spending	Concentrate qualifying expenses in years with sufficient tax liability
Hire qualifying employees early in the year	WOTC requires Form 8850 within 28 days of start date, and it only covers hires who began work before 2026 unless Congress extends it
Coordinate energy credits with depreciation	Energy ITC reduces depreciable basis; plan for the net benefit
Carry back excess credits	Amend the prior year’s return to use credits that exceed the current year’s limitation
Use Section 41(h) payroll offset	Startups can use R&D credits against payroll tax even with no income tax liability
Stack credits strategically	Combine WOTC + R&D + energy + disabled access in the same year for maximum reduction

Illustrative numbers only, not a real client and not advice for your facts.

How does the small business health care tax credit work?

The small business health care tax credit under IRC 45R provides up to 50% of employer-paid premiums (35% for tax-exempt employers) for businesses that cover at least 50% of employee-only premium costs. To qualify, you must have fewer than 25 full-time equivalent employees with average annual wages below $67,000 (2025, indexed), and you must purchase coverage through the SHOP marketplace. The credit is calculated on a sliding scale, with the maximum credit available only to employers with 10 or fewer FTEs and average wages of $33,300 or less (2025). You can claim this credit for only two consecutive tax years, so timing the credit to coincide with your highest premium costs maximizes its value. The credit is claimed on Form 8941 and reduces your tax liability directly.

Want this checked against your own situation?

Start with a Diagnostic: a CPA licensed in the US and Canada reads your file and tells you in writing what's wrong and how to fix it, three to four business days after you finish the questions. The report is $250. If you hire us for any work after that, you get the $250 back as a discount on that work. Or send us your return or your letter and get a fixed price, free.

Start a Diagnostic →See prices

Get a fixed price, free

Get the next cross-border guide by email

One or two plain-English guides a week on US-Canada tax. No spam, unsubscribe anytime.

Cite this page

Yarik Yarosh, CPA. "General Business Credit: How Tax Credits Work Together and the Carryback and Carryforward Rules Under IRC 38." Blue Cloud CPA, September 5, 2026, updated October 19, 2026. https://bluecloudcpa.com/guides/small-business-general-business-credit-carryback-carryforward-rules

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.

General Business Credit: How Tax Credits Work Together and the Carryback and Carryforward Rules Under IRC 38

How do business tax credits work together?

How does the small business health care tax credit work?

Related guides