Last updated: October 5, 2026.

If a window sales page still tells you that new 2026 windows automatically qualify for a 30% federal tax credit, slow down and check the date. The major federal home-improvement credit that covered qualifying windows ended for property placed in service after December 31, 2025.

What Changed for 2026?

The IRS states that the Energy Efficient Home Improvement Credit cannot be claimed for property placed in service after December 31, 2025. ENERGY STAR’s window tax-credit page likewise lists the eligible purchase-and-installation period as January 1, 2023 through December 31, 2025.

That does not mean ENERGY STAR-certified windows disappeared. The efficiency label and the federal tax credit are separate things.

ENERGY STAR Window Criteria Still Exist

ENERGY STAR continues to certify residential windows, doors, and skylights under its current performance criteria. Windows are evaluated using measures that include U-Factor and, where applicable, Solar Heat Gain Coefficient based on climate zone.

The agency says certified windows, doors, and skylights can reduce heating and cooling costs compared with non-certified products, with average savings varying by home, climate, existing windows, and installation.

What Is U-Factor?

U-Factor describes how readily a window transfers heat. Lower values generally indicate better resistance to heat flow.

That matters in both winter and summer because a window is part of the building envelope. But one rating should not be used alone.

What Is Solar Heat Gain Coefficient?

Solar Heat Gain Coefficient, or SHGC, describes how much solar radiation passes through the window as heat. The right balance can depend on climate, orientation, shade, and how the room is used.

A window that is appropriate for one region or exposure may not be the best choice somewhere else, which is why climate-zone criteria are useful.

Installation Can Matter as Much as the Label

An efficient window installed poorly can still leak air or water. Before accepting a quote, ask how the installer will handle flashing, sealing, trim, existing damage, insulation around the opening, and exterior water management.

If the opening has rot, moisture damage, or structural problems, clarify whether repair is included or will be priced separately.

Compare the Whole Quote

• Exact window series and model
• Frame material and finish
• Glass package and efficiency ratings
• Removal and disposal of existing windows
• Interior and exterior trim work
• Installation labor
• Warranty terms
• Permit costs if applicable
• Financing terms and total repayment cost

A large advertised discount can still produce a higher final price than a smaller promotion from another installer. The installed total and scope matter more than the percentage in the ad.

Check for Local Incentives

Although the federal 25C tax credit ended, some utilities, states, local agencies, or other programs may offer incentives for energy-efficiency improvements. Availability varies. Verify the current program directly and make sure the exact window product and project qualify before counting the incentive in your budget.

Related reading: Are high-performance windows worth it? · Double-pane vs. triple-pane windows · When should you consider replacing your windows?

The Bottom Line

The end of the federal window tax credit changes the math, not the value of comparing efficient products. In 2026, shop based on performance ratings, climate fit, installation quality, warranty, and the complete price. If a seller uses an old federal tax-credit claim, ask them to show the current rule before relying on it.

Sources: IRS Publication 530 — Termination of Home Energy Credits; ENERGY STAR — Windows & Skylights Tax Credit; ENERGY STAR — Current Window Performance Criteria.