Replacement Windows · Exterior Doors
The windows & doors rebate stack
Replacement windows are the most expensive envelope upgrade per square foot. The IRA 25C credit makes the math work better than it has in years — but the per-item caps mean planning matters.
Federal credit (25C)
| Measure | Cap | Per-item cap | Requirement |
|---|---|---|---|
| Exterior windows & skylights | $1,200 envelope | $600/year total | ENERGY STAR Most Efficient |
| Exterior doors | $1,200 envelope | $250/door, $500/year total | ENERGY STAR |
The $600 windows cap and $500 doors cap reset every tax year. A homeowner doing a whole-house window replacement spread across two tax years can claim $1,200 total instead of $600.
Utility rebates
Window rebates are uneven by utility. Some run $25-$100 per window for ENERGY STAR Most Efficient; others have stopped offering window rebates entirely. Check your utility before assuming a rebate exists.
State programs
NYSERDA, Mass Save, Energy Trust of Oregon, and Efficiency Maine include windows in their whole-home incentive packages. CA, MD, NJ have window-specific rebates tied to net-metering or low-income weatherization.
ENERGY STAR Most Efficient windows — the federal floor
ENERGY STAR Most Efficient is the top 5% of certified windows. They typically have a U-factor ≤ 0.20 and SHGC ≤ 0.25 (varies by climate zone). When buying, get the NFRC label numbers (U-factor, SHGC, VT, AL) — those determine eligibility, not marketing copy.
Door requirements
Just ENERGY STAR certification (any tier) for doors — not "Most Efficient." Cap is $250 per door, max 2 doors per year.