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Deadline aheadLive at 30%, but any project starting construction now must be placed in service by December 31, 2027 or the credit is zero. There is no phase-down. It is a cliff.

IRC Section 48E · Form 3468 · Tax credit

Commercial Solar Investment Credit

30% of project cost, but the clock is short and the residential version is already dead

Projects starting now must be in service by December 31, 2027. Hard cliff, no phase-down.

Who it is forBusinesses installing solar on commercial property they own. Most commercial rooftop systems qualify for the full 30% with no prevailing wage requirements.

What it is worth30% of qualified project cost, plus up to 20 more percentage points from domestic content and energy community bonuses. On a $300,000 system the base credit is $90,000.

Where it is claimedForm 3468, under IRC Section 48E

Why businesses miss this one

Most people think this died with the residential credit. It did not. The homeowner credit ended December 31, 2025. The commercial credit is still 30% today. Almost nobody is explaining the difference correctly.

How the money actually works

The base credit is 6% of qualified investment, rising to 30% if prevailing wage and apprenticeship requirements are met.
Systems with maximum net output under 1 megawatt AC get the full 30% automatically, with no prevailing wage or apprenticeship burden at all. That covers nearly every commercial rooftop installation.
Note that the 1 megawatt threshold is measured in alternating current, not direct current. A system well over 1 MW DC can still qualify.
Domestic content adds 10 percentage points. Energy community location adds another 10. Both stack, taking the credit to 50%.
The credit can be sold for cash to another taxpayer, or claimed as a direct payment by tax-exempt entities. Both require registering with the IRS before filing.
That transferability is why a business with little tax liability can still convert the credit into cash. This is as much a capital access question as a tax question.
Depreciable basis is reduced by half the credit. A $100,000 system generating a $30,000 credit leaves $85,000 of depreciable basis, which is then eligible for 100% bonus depreciation.

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What to gather before you call anyone

Organized records are the difference between a preparer who says it is not worth the trouble and one who finds the money. Have these ready.

Construction start documentation, which determines whether you are grandfathered
Interconnection agreement and utility approval, since placed in service requires both completion and interconnection
Supplier certifications for panels, inverters, and racking to satisfy foreign entity restrictions
IRS pre-filing registration number if you intend to sell the credit or claim direct payment
Domestic content cost documentation if claiming that bonus
Form 3468 with the return

Disqualifiers and traps

These are the places claims fall apart, either at filing or on examination.

The December 31, 2027 placed-in-service date is a cliff, not a phase-down. Miss it and the credit is zero. Placed in service requires utility interconnection, and interconnection queues are the schedule killer that catches most projects.
The grandfathering window for construction starts closed July 4, 2026. Anything beginning now is on the 2027 clock.
Foreign entity restrictions apply to every new project with no small-project exemption. A 200 kW rooftop array must still clear the material assistance cost ratio, which means real supplier diligence.
The five-year accelerated depreciation that solar used to get is gone for projects starting now. Many solar sales decks still show it.
There is a five-year recapture period. Selling the building within five years triggers recapture. If you plan to exit inside that window, a lease or power purchase agreement is often the better structure than owning the asset.
The low-income community bonus is a competitive allocation, not something you self-certify, and the 2026 program year has already closed.
The IRS energy community mapping tool is informational only and cannot support a return position on its own.

One more thing worth knowing

The residential credit under Section 25D is dead for anything completed after December 31, 2025, and the test is installation completion, not payment date. A homeowner who paid in full in November 2025 but whose installer finished in January 2026 gets nothing. That is a different rule from the commercial credit described here.

Sources

Every figure on this page traces to one of these. All verified August 14, 2026.

Other programs

FICA Tip CreditAvailable now
Research and Development Tax CreditAvailable now
Section 179 and Bonus DepreciationAvailable now
Cost SegregationAvailable now
Qualified Production PropertyDeadline ahead
Work Opportunity Tax CreditNot available

This is educational information, not tax advice. Big Brain Funding is not a CPA firm, an enrolled agent, or a tax preparer. We do not prepare, file, or sign tax returns, and we do not determine whether any business is eligible for any tax program. Eligibility depends on facts specific to your business and on tax law that changes. Nothing here is a promise of a refund, a credit, or a deduction amount. Confirm everything with a licensed CPA or enrolled agent before you file or amend a return.

Program details on this page were verified against official IRS and government sources on August 14, 2026. Tax law changes, sometimes mid-year. Check the linked sources for the current position before acting.