Both the residential solar credit and the Section 25C Energy Efficient Home Improvement Credit were terminated by the One Big Beautiful Bill Act, effective December 31, 2025. But homeowners who replaced qualifying windows before that deadline can still claim Section 25C on their 2025 federal tax return. If you upgraded windows last year and haven't filed yet, you still have time to capture the credit.
The 30% Cap and the Two-Tax-Year Strategy That Could Mean $1,200 Back
Section 25C reimburses 30% of the cost of qualifying windows, capped at $600 per tax year. That per-year structure rewarded homeowners who spread a full-home replacement across two calendar years: replacing half before December 31, 2024, and the rest in 2025 allowed a $600 claim on each return, for a combined $1,200.
Homeowners who completed a full replacement entirely in 2025 can still claim up to $600 when they file this year. Either way, the window to claim closes with the 2025 return — there is no 2026 installation path to this credit.
ENERGY STAR Most Efficient: Why the Label on the Box Isn't Enough
Not every ENERGY STAR-labeled window qualifies for Section 25C. The law requires windows to meet the ENERGY STAR "Most Efficient" certification — a considerably higher bar than standard ENERGY STAR.
Most Efficient windows must hit stringent U-factor and Solar Heat Gain Coefficient (SHGC) thresholds that vary by climate zone. Under ENERGY STAR Version 7.0, Northern zone windows must achieve a U-factor at or below 0.22, a standard that makes triple-pane glass the practical choice for many Northern homeowners. Builder-grade replacements almost never qualify. Before claiming the credit, verify that your specific model appears on the ENERGY STAR Most Efficient certified products list at energystar.gov and keep that documentation with your tax records.
State and Utility Programs That Survived the Federal Rollback
Federal incentives are gone for new 2026 installations, but several state and utility programs remain active and can significantly reduce the cost of a window project on their own.
Massachusetts
Massachusetts homeowners can access Mass Save rebates — administered by the state's electric and gas utilities — which offer per-window rebates on qualifying ENERGY STAR certified replacements installed through a participating contractor. A no-fee Mass Save Home Energy Assessment is required to unlock the rebate.
New York
New York residents should look to NYSERDA's Comfort Home program, which offers tiered incentives on high-performance windows paired with insulation packages. Income-eligible households may qualify for EmPower+, which can cover a substantially larger share of qualifying improvements.
Pacific Northwest
Puget Sound Energy offers a dedicated residential window rebate program for Washington customers, and Pacific Power serves Oregon, Washington, and California customers with home efficiency incentives.
California
California homeowners should check directly with their utility provider, as PG&E, Southern California Edison, and SoCalGas have each maintained weatherization and window incentive programs at the utility level, though availability and amounts vary.
The Manufacturer Registration Requirement: Why the Wrong Window Can Sink Your Claim
Claiming Section 25C requires more than buying a qualifying product. The manufacturer must be IRS-registered and must provide a Qualified Manufacturer Identification Number (QMID) — entered on Form 5695 when you file.
Purchasing from a non-registered manufacturer disqualifies the credit entirely, even if the product meets ENERGY STAR Most Efficient criteria. Before filing, obtain the QMID from the manufacturer and confirm it in the IRS Energy Credits Online registry. Manufacturers that sell primarily through big-box channels are not always registered.
Vinyl, Fiberglass, or Wood-Clad: Why Fiberglass Is Winning the Market for Eligible Installs
Material choice directly affects whether a window can reach ENERGY STAR Most Efficient thresholds — which matters both for the federal filing and for qualifying under state rebate programs that use the same standard.
- Vinyl windows dominate the replacement market by volume but many models fall just short of Most Efficient U-factor requirements, particularly in Northern zones.
- Wood-clad windows are thermally capable but carry higher cost and maintenance demands.
- Fiberglass has become the dominant choice for credit- and rebate-eligible installs. It expands and contracts at nearly the same rate as glass for better long-term seals, and fiberglass-framed products are disproportionately represented among ENERGY STAR Most Efficient certified models. Several manufacturers have specifically engineered their fiberglass lines around Most Efficient criteria.
The Math Still Works — Even Without the Federal Credit
Homeowners who replace windows for energy savings alone typically see payback periods of seven to twelve years, depending on climate, home size, and how leaky the old windows were. The federal credit is closed for new installations, but the 2026 filing deadline is still real — and the state programs that remain are worth pursuing regardless.