For a few years, businesses had to spread domestic research and development costs over several years instead of deducting them right away.
That changed.
Although this article is focused on 2026 planning, the restored domestic R&D expense deduction 2026 generally applies to tax years beginning after December 31, 2024. Under Section 174A, qualifying domestic research or experimental expenses may generally be deducted in the year they are paid or incurred.
But that does not mean every business should immediately amend its 2022, 2023, or 2024 returns.
The special retroactive election for certain small businesses generally had to be made by July 6, 2026. For some 2022 returns, the normal refund-claim deadline may have required action even earlier.
If that deadline was missed, do not assume the old returns can still be reopened under that special rule. There may still be a deduction available for remaining unamortized domestic Section 174 costs, but those amounts have their own transition rules.
Before filing, ask: What was reported before, and what procedure applies now?
- How the Domestic R&D Expense Deduction 2026 Changed
- Mistake 1: Assuming the New R&D Deduction Automatically Reopens Prior Returns
- Mistake 2: Missing the July 6, 2026 Retroactive Election Deadline
- Mistake 3: Confusing Old Amended Returns With Remaining Unamortized R&D Costs
- Mistake 4: Assuming Everything in the “R&D” Account Qualifies
- Mistake 5: Ignoring the Research Credit and Section 280C
- Mistake 6: Using an Amended Return When the Real Issue Is an Accounting-Method Change
- What Small Businesses Should Review Before Amending Anything
- Records to Review Before Making a Change
- What If the July 6, 2026 Deadline Was Missed?
- Special Issues for Partnerships
- When Small Businesses Should Get Professional Help
- FAQs About the Domestic R&D Expense Deduction 2026
How the Domestic R&D Expense Deduction 2026 Changed
Section 174A generally restored a current deduction for qualifying domestic research or experimental expenses paid or incurred in tax years beginning after December 31, 2024.
A business can also elect to capitalize qualifying domestic costs and amortize them over at least 60 months.
That is different from the rules businesses dealt with for tax years beginning after December 31, 2021, and before January 1, 2025. During those years, domestic research expenses generally had to be capitalized and amortized over five years.
Foreign research still follows different rules and generally remains subject to 15-year amortization.
Revenue Procedure 2025-28 transition rules lay out IRS transition procedures for Section 174A, including certain elections and accounting-method changes.
New domestic R&D costs and older capitalized costs are not always handled the same way.
Current domestic R&D costs, prior-year amended returns, and remaining unamortized Section 174 balances can require different procedures.
Mistake 1: Assuming the New R&D Deduction Automatically Reopens Prior Returns
A business owner may hear that immediate R&D deductions are back and think, “Great, let’s amend the old returns.”
That can be the wrong first move.
A company may still have domestic research costs from 2022, 2023, or 2024 on an amortization schedule. The new law does not automatically let the business claim everything at once on an amended return.
There were special transition options, each with its own rules and deadlines.
Before changing an older return, check how the costs were reported, whether the business qualified for the relief, whether an election was made, and whether the deadline was still open.
The right procedure could involve an amended return, an Administrative Adjustment Request, Form 3115, or a statement filed with a return.
Mistake 2: Missing the July 6, 2026 Retroactive Election Deadline
Certain qualifying small businesses were allowed to apply the new Section 174A treatment retroactively to domestic research or experimental costs from 2022 through 2024.
For an eligible business, that could replace the prior five-year domestic amortization treatment with a current deduction for those earlier years.
But the special retroactive election generally had to be made by July 6, 2026.
For some 2022 returns, the normal deadline for claiming a refund may have arrived sooner. The IRS explains the general time limits for claiming a credit or refund.
As of August 2026, a business should not prepare an amended return on the assumption that this special election is still open.
“Small business” also has a specific meaning here. Eligibility depends on the applicable gross-receipts test and other restrictions, including tax-shelter rules.
If the election was missed, the better question is: What remaining domestic Section 174 balance do we have, and how should it be handled now?
The expired retroactive election and the remaining unamortized domestic Section 174 balance are separate issues.
Mistake 3: Confusing Old Amended Returns With Remaining Unamortized R&D Costs
Missing the retroactive election does not automatically answer what happens to domestic Section 174 costs that are still being amortized.
Those remaining balances have separate transition rules.
A business that capitalized domestic research costs during 2022 through 2024 may still have a balance left on its books.
The transition rules allow taxpayers to recover the remaining unamortized domestic amount in full in the first post-2024 tax year or spread it over that year and the following tax year.
For a calendar-year business, that generally points to 2025 alone or 2025 and 2026, depending on the method selected.
The remaining deduction may need to be handled through the transition method rather than reopening each original year.
If the 2025 return has already been filed, check what method was actually used before changing anything else.
Mistake 4: Assuming Everything in the “R&D” Account Qualifies
A general ledger account named “R&D” is a starting point. It is not a tax conclusion.
You still need to look at what the business paid for.
Section 174A covers domestic research or experimental expenditures, including amounts paid or incurred in connection with software development.
Actual software-development work may receive specific treatment under Section 174A. But purchases, licensing, hosting, maintenance, implementation, and routine IT work are not automatically development costs.
The same review applies to wages, contractors, prototypes, testing, engineering, and supplies.
Location matters too. If developers, engineers, or contractors worked outside the United States, separate those costs before applying the domestic rules.
Keep project records tied to the tax treatment, not just the name of the general ledger account.
Mistake 5: Ignoring the Research Credit and Section 280C
The domestic R&D deduction and the Section 41 research credit are related, but they are not the same thing.
A cost may be treated as a research or experimental expenditure under Section 174A without qualifying for the research credit.
The credit has its own requirements, including technological information, a permitted business purpose, and a process of experimentation.
If the business claimed the research credit, review Form 6765 research credit instructions and the supporting workpapers before changing the expense treatment.
Section 280C also needs to be part of the review.
If the business does not make the reduced-credit election, the domestic research or experimental expenses otherwise deducted or capitalized under Section 174A generally must be reduced by the research credit.
Changing the deduction without checking the credit can create a mismatch.
Review the Section 174A treatment, Form 6765, any Section 280C election, and the underlying project records together.
IRSProb’s guide to R&D tax credit claim documentation can help frame the records needed for research credit issues.
Mistake 6: Using an Amended Return When the Real Issue Is an Accounting-Method Change
Not every R&D correction belongs on an amended return.
Some changes are accounting-method changes.
Revenue Procedure 2025-28 includes procedures for taxpayers moving to the current Section 174A deduction method, choosing capitalization, or recovering certain remaining unamortized domestic Section 174 amounts.
An automatic accounting-method procedure may apply, and in some cases the transition guidance allows a statement instead of a full Form 3115 accounting method change.
For remaining unamortized domestic Section 174 amounts, current Form 4562 instructions also matter. They address reporting these amounts on line 43 and point taxpayers back to Revenue Procedure 2025-28.
First determine what kind of change is being made. Then determine whether the filing requires an amended return, AAR, Form 3115, Form 4562 statement, or another procedure.
What Small Businesses Should Review Before Amending Anything
Before changing a return, pull the full R&D history together.
Review:
- Which years include domestic research or experimental costs
- How those costs were originally reported
- How much remains unamortized
- Whether the business qualified for the special small-business election
- Whether an election was filed by July 6, 2026
- Whether an earlier refund-claim deadline applied
- Whether the Section 41 research credit was claimed
- Whether Section 280C affected the deduction
- Whether any research was performed outside the United States
- Whether the taxpayer is a partnership subject to BBA procedures
- What the 2025 return already reflects
- What treatment is planned for 2026
IRSProb’s guide to Texas R&D tax credit 2026 may also be useful for Texas businesses reviewing state-level research credit issues.
Records to Review Before Making a Change
Start with the 2022 through 2025 federal tax returns and any Section 174 amortization schedules.
That may include payroll reports, contractor invoices, project descriptions, software-development records, testing documents, engineering notes, general ledger accounts, and records showing where the work was performed.
If a research credit was claimed, review Form 6765, the credit calculations, supporting studies, and any Section 280C election.
Also look for earlier Forms 3115, method-change statements, amended returns, or partnership AARs.
For any remaining unamortized domestic Section 174 balance, review current Form 4562 instructions and determine whether a statement is required under the transition procedure.
The goal is to understand how the costs moved through the returns before changing the treatment.
IRSProb’s guide to small-business tax records explains why documentation matters before changing a business tax position.
What If the July 6, 2026 Deadline Was Missed?
Missing the special retroactive election deadline does not automatically mean every remaining R&D deduction is gone.
It does mean that election should not be treated as if it were still available.
The business should review its remaining unamortized domestic Section 174 balance, the transition method already used, and the treatment shown on the 2025 return.
New domestic research expenses also need to be handled correctly under Section 174A going forward.
Do not try to recreate the expired election through another filing method unless there is authority to do so.
A separate correction may still be possible for another issue, but it has its own facts, deadline, and procedure.
Special Issues for Partnerships
Partnerships need another layer of review.
A partnership subject to the Bipartisan Budget Act centralized partnership audit regime generally uses an Administrative Adjustment Request, or AAR, to correct partnership-related items instead of filing a traditional amended return.
The IRS provides guidance on BBA partnership AAR procedures.
Before changing R&D treatment, confirm whether the BBA rules apply and how the adjustment will flow to the partners.
When Small Businesses Should Get Professional Help
Professional review makes sense when the business has a large Section 174 balance, foreign research, prior research credits, Section 280C issues, software-development costs, partnership complications, or several affected tax years.
It is also worth getting help when the July 6, 2026 election deadline was missed or the business is unsure whether the change belongs on an amended return or through an accounting-method procedure.
IRSProb’s guide to tax planning strategies explains why timing, credits, deductions, and future returns should be reviewed together.
Need help reviewing R&D deductions, credits, or prior returns?
IRSProb.com helps business owners review tax notices, amended returns, business deductions, payroll issues, credits, and reporting problems when the next step is not clear.
Visit IRSProb.com or call 214-214-3000.
Request a Free Tax ConsultationFAQs About the Domestic R&D Expense Deduction 2026
When did the restored domestic R&D deduction begin?
Section 174A generally applies to qualifying domestic research or experimental expenditures paid or incurred in tax years beginning after December 31, 2024.
Can a small business still amend a 2022 return for R&D expenses?
The special small-business retroactive election generally had to be made by July 6, 2026. Some refund claims may have had an earlier deadline. Other types of corrections can follow different rules.
Can remaining Section 174 costs still be deducted?
They may be. Remaining unamortized domestic Section 174 costs have their own transition rules even if the special retroactive election was missed.
Can the remaining balance be deducted all at once?
The transition rules allow an election to recover the remaining amount in full in the first post-2024 tax year or ratably over that year and the following tax year.
Is software development treated as R&D?
Amounts paid or incurred in connection with software development can receive Section 174A treatment, but routine software purchases, maintenance, hosting, implementation, and licensing should be reviewed separately.
Are foreign R&D expenses deductible under Section 174A?
Section 174A applies to domestic research or experimental expenses. Foreign research continues to follow separate capitalization and 15-year amortization rules.
Is the R&D deduction the same as the research credit?
No. Section 174A deals with the tax treatment of domestic research or experimental expenses. Section 41 provides a separate research credit with its own qualification rules.
When is Form 3115 involved?
Form 3115 may be involved when the change is an accounting-method change. Some transition procedures may allow a statement instead, so applicable IRS procedure should be reviewed first.
