Real Solar Costs

Signed in 2025, Installed in 2026? The Solar Tax-Credit Timing Trap

By Mueez Published

Signed in 2025, Installed in 2026? The Solar Tax-Credit Timing Trap

You signed your solar contract near the end of a calendar year. The installer was booked solid, permitting dragged on, and your panels finally went up in the new year — a few months after the paperwork was signed. You assumed the 30% federal residential solar tax credit applied [2], because that was the deal on the table when you signed. Here is the part of the tax code that can turn that assumption into an expensive surprise: for the residential clean energy credit, the IRS looks at when the installation was completed — not when you signed the contract [1]. And for property placed in service after December 31, 2025, the 25D residential credit terminates [2].

Rows of solar panels under a bright blue sky — the completion date of a system like this is what the IRS counts for the residential tax credit
Photo: Unsplash

The rule: completion date, not contract date

The IRS guidance on the home energy credits is explicit: residential clean energy expenditures are counted when the original installation is completed, and an expenditure is treated as made when the installation is finished [1]. Your deposit, your signed contract, even a down payment made in 2025 do not change the timing — the credit follows the finish line, not the starting gun [1].

That matters because the 25D credit is a 30% credit only for property placed in service from 2022 through 2025 [2]. For property placed in service after December 31, 2025, the credit terminates [2]. So the question that decides everything is simple: was your system placed in service on or before December 31, 2025 [2]? If the answer is yes, the 30% rate applies [2]; if the installation crossed into 2026, the residential credit is gone [1][2].

Does the 25D credit apply? Follow the dates [1] Was the installation completed and the system placed in service? On or before Dec 31, 2025 30% credit applies [2] After Dec 31, 2025 25D credit terminates [2] The construction-window safe harbor covers only the commercial credit (48E) — it does not apply to 25D [1] Contract-signing date alone never decides the credit
Figure 1: The 25D timing test. The credit follows completion and placed-in-service timing, and the commercial-credit construction safe harbor does not rescue a homeowner-owned 25D claim [1][2].

The safe-harbor trap that catches homeowners

Somewhere in the post-credit confusion, a rumor spread: that a project could still qualify if construction began within a one-year window before the deadline. That window exists — but it belongs to the commercial credit under section 48E, not to the residential 25D credit [1]. It does not apply to a system you own on your own roof.

Why does the distinction matter? Because in a lease or power-purchase agreement (PPA), the installer owns the system and claims the commercial credit — that is the situation where the 48E safe harbor can apply [1]. If you bought your system outright or financed it, you are in 25D territory, where the only date that counts is when the original installation was completed and the system was placed in service [1][2].

What "placed in service" looks like in practice

The IRS frames the test as completion of the original installation [1]. In everyday terms, that means the job is done and the system is ready to operate — not merely that panels are on the roof or that a deposit cleared. Installers know that permit inspections and utility permission-to-operate can add weeks between "panels mounted" and "system running," and those weeks are exactly what can push a late-year project across the December 31 line [1].

None of this means you need to guess your way through it. The practical move is documentation: keep the signed contract, the installer's completion record, the final inspection sign-off, and the date the system first operated. If your system was placed in service before the cutoff and your credit exceeds your tax liability, unused credit may be carried forward [2] — another reason the completion paperwork matters.

Close-up of solar panel rows in a sunny field — keep your contract, inspection sign-off, and first-operation date as timing proof for your tax records
Photo: Unsplash

Your timing checklist

  • Ask your installer for a completion date in writing — not an install-start estimate. The IRS tests the expenditure against completion [1].
  • Confirm which credit your arrangement uses. Owned system: 25D timing rules [1]. Lease or PPA: the installer's commercial credit, where the 48E safe harbor may apply [1].
  • If you missed the cutoff, do not claim the credit anyway. 25D is 30% for property placed in service 2022–2025 and terminates for property placed in service after December 31, 2025 [2].
  • Check carryforward. If you qualified but the credit exceeds your tax liability, unused amounts may be carried forward [2].
  • Verify the current rules before you file. Tax law around these credits has changed recently; confirm your situation against the current IRS guidance or a tax professional before acting [1][2].

The bottom line is short: signatures do not place systems in service — completed installations do [1]. For the 25D credit, the finish date is the whole game [1].

Sources

  1. IRS, "Understanding the Home Energy Credits" — https://www.irs.gov/EnergyCreditFAQs
  2. IRS, Residential Clean Energy Credit — https://www.irs.gov/credits-deductions/energy-efficient-home-improvement-credit

Verified: 2026-10-12

Disclosure: This article was drafted with AI assistance and reviewed by a human editor. Figures reflect sources available on the verified date; confirm current program rules before acting.