Window Tax Credit 2026: Section 25C & California Stacking

The federal window tax credit in 2026 is gone for new installs. Section 25C, the Energy Efficient Home Improvement Credit that capped window credits at $600 per year, expired December 31, 2025 under the One Big Beautiful Bill Act (P.L. 119-21), signed into law on July 4, 2025. There is no equivalent federal credit for residential window replacement in 2026 (IRS, 2025).

That is the headline. But for most California homeowners reading this, it is not the whole story. If you installed qualifying ENERGY STAR Most Efficient windows in 2025 — a project that wrapped up before New Year's — you can still claim up to $600 in Section 25C credits on the 2025 return you file in 2026. And for 2026 projects in Placer County, Auburn, Colfax, and the rest of the Sierra Foothills, there are state, utility, and insurance incentives that can stack into meaningful dollar amounts when you know how to combine them.

I'm John, owner of Colfax Glass. I've been installing windows in the Sierra Foothills for 25+ years, and the last 18 months of tax law churn have created the most confusing incentive environment I've seen. Half the websites still ranking for "window tax credit 2026" were written before the One Big Beautiful Bill passed and never got updated. This guide fixes that — straight from the IRS guidance, the California Energy Commission updates, and what we are actually seeing on quotes today.

Section 25C of the U.S. tax code — the Energy Efficient Home Improvement Credit — was the main federal tax credit for residential window replacement. It allowed homeowners to claim 30% of the cost of qualifying windows and skylights, capped at $600 per taxpayer per year, with a $1,200 overall annual cap on building envelope improvements (IRS, 2025). The credit was originally extended through December 31, 2032 under the Inflation Reduction Act of 2022.

That extension was repealed early. The One Big Beautiful Bill Act, signed July 4, 2025, accelerated the sunset of Section 25C and its companion clean-energy credit, Section 25D. Both credits ended for property placed in service after December 31, 2025. The IRS confirmed this in late-2025 guidance and it is reflected in the 2025 Instructions for Form 5695.

This matters for 2026 in three specific ways. First, anyone whose project finished in 2025 still has one filing window to claim the credit. Second, anyone budgeting a 2026 project off old contractor quotes that mention "$600 federal tax credit" is working with stale numbers — that line item is no longer valid. Third, the absence of a federal credit pushes more weight onto state-level California incentives, which are now the only meaningful financial offsets available outside of the project itself.

Yes. If your qualifying windows were installed and placed in service on or before December 31, 2025, you can claim the Section 25C credit on your 2025 federal tax return — even though you are filing it in 2026. The credit applies based on when the windows were placed in service, not when you file (IRS, 2025).

We finished a 14-window full-frame project in Auburn the week before Thanksgiving 2025. The homeowner had been on the fence about timing for months. When the OBBB passed in July, that decision made itself — install before year-end or lose the $600. The total project came in around $11,400, which made the 30% × cost calculation max out at the $600 cap. They will claim it on Form 5695 with their April 2026 filing.

A few rules trip people up. The credit is non-refundable, meaning it can reduce your tax liability to zero but cannot generate a refund beyond what you owed. It cannot be carried forward to 2026 either — if your 2025 tax liability was below $600, the unused portion is lost. And it only applies to windows that met the ENERGY STAR Most Efficient certification, not the standard ENERGY STAR label.

To qualify for the Section 25C credit, windows had to meet ENERGY STAR Most Efficient criteria for the climate zone where the home is located — not just the standard ENERGY STAR certification (EPA ENERGY STAR, 2025). For California's Northern climate zone, that meant a U-factor of 0.20 or lower and an SHGC of 0.40 or lower for most product categories.

This is a meaningful gap. A standard ENERGY STAR window for the California Southern climate zone allows a U-factor up to 0.32 and meets state code at the prescriptive level. ENERGY STAR Most Efficient windows are typically triple-pane or premium dual-pane with high-performance Low-E coatings and inert gas fills. A homeowner who installed windows that met state Title 24 requirements but not Most Efficient criteria did not qualify for the federal credit, even if their installer told them they did.

This caught a fair number of homeowners during the 2024 and 2025 filing seasons. Standard double-pane Low-E vinyl windows that hit a 0.27 U-factor for Climate Zone 11 compliance did not automatically qualify for the 30% federal credit. The IRS required documentation — typically the manufacturer's NFRC label and an ENERGY STAR Most Efficient designation listed in the certified products database. Without it, the credit was denied on audit.

With Section 25C gone, the financial incentives for 2026 California window projects are state, utility, and insurance-based — not federal. There are four programs worth knowing about for Sierra Foothills homeowners, and the California wildfire home hardening grants for windows post covers the wildfire-specific programs in detail. Here is the broader 2026 stacking landscape.

The FAIR Plan and Safer from Wildfires regulation requires California insurance carriers to offer rate reductions for home hardening measures, including multi-pane windows. According to the California Department of Insurance, the FAIR Plan offers up to 16.4% premium discounts when multiple hardening measures are documented (CDI, 2025). For a $4,500 annual premium, that is $738 per year — recurring savings that can outweigh the one-time $600 federal credit over a 5- to 10-year period.

The California Wildfire Mitigation Program (CWMP), funded through FEMA and Cal OES, covers fire-resistant window upgrades at no cost to qualifying homeowners in active project areas. The program prioritizes low- to moderate-income households in High and Very High Fire Hazard Severity Zones. As of spring 2026, Placer County has active CWMP project areas, and we have helped customers in Colfax and Foresthill apply.

Utility-side, PG&E and SMUD do not currently offer dedicated window rebates, but both have whole-home energy audit programs that can identify window upgrades as part of broader retrofits. SMUD's Home Performance Program provides partial rebates when windows are installed alongside qualifying HVAC upgrades. PG&E's residential rebate finder lists windows under "limited-time programs" that vary by region — call before relying on any specific dollar amount.

Stacking is where Sierra Foothills homeowners can recover real money in 2026, even without the federal credit. The principle is simple: combine programs that reward different things — code compliance, fire hardening, insurance behavior, and utility participation — into one project. Here is the order I recommend going through them.

Start with code. California's Title 24 2025 standards took effect January 1, 2026 and require a U-factor of 0.27 for Climate Zones 11 and 12, which covers Auburn, Colfax, Roseville, Rocklin, and Sacramento. A permitted window replacement in California in those zones must hit those numbers. Selecting windows that meet the Title 24 prescriptive path avoids the cost of a HERS rater certifying the alternative compliance path — which can run $400 to $800 per project. That is real savings, even if it does not feel like an incentive.

Next, layer the FAIR Plan discount. If your home is in a High or Very High Fire Hazard Severity Zone — and most foothills homes between 1,500 and 4,500 feet of elevation are — multi-pane windows count toward the Safer from Wildfires hardening checklist. Document the install with NFRC labels and contractor invoices, and submit them to your insurer. The premium discount applies as long as the windows remain in place and is recurring annually.

Third, evaluate the CWMP if you qualify on income and zone. The program does not stack with itself in the sense that it covers full project costs — there is no out-of-pocket to credit. But if you qualify for CWMP windows and ALSO upgrade adjacent fire-resistant components (decking, vents, soffits) outside the grant scope, the FAIR Plan discount applies to the full hardening picture, not just the granted windows.

A typical 10-window full-frame replacement in the Sierra Foothills runs $7,000 to $12,000 installed in 2026, with our Auburn and Colfax averages landing right in the middle of that range. The same project would have netted a $600 federal credit in 2025 — which is gone. But properly stacked California incentives can offset more than that on the right home, particularly when insurance discounts compound over multiple years (HomeAdvisor, 2026).

Here is a real numbers example. A Colfax customer last fall planned a 12-window project at $9,800. They had pencilled in $600 from Section 25C, expecting an effective net of $9,200. Because they pushed the install into late January 2026, they lost the federal credit. But their home sits in a Very High Fire Hazard Severity Zone. With Milgard's Tuscany Series fire-resistant dual-pane windows installed and documented to FAIR Plan, their hardening discount cut their annual premium from $4,820 to $4,031 — a $789 annual savings. Over five years, that is $3,945 in recurring savings against the one-time $600 that was lost.

Triple-pane ENERGY STAR Most Efficient windows still make sense for a subset of homes — those near I-80, the railroad tracks, or planning to stay 15+ years and prioritizing maximum efficiency. They cost $1,000 to $1,500+ per window, more than standard energy-efficient windows California 2026, but they hit performance levels that pay back faster on energy alone. The federal credit no longer underwrites the premium, but Title 24 compliance is automatic and FAIR Plan discounts apply equally.

It is reasonable to ask whether Congress could reinstate Section 25C or pass a successor credit. As of April 2026, no active legislation has been introduced to restore the residential energy efficiency credits, and the political climate around the One Big Beautiful Bill makes near-term reversal unlikely. The credits were repealed as part of broader fiscal trade-offs, and reinstating them would require either standalone legislation or inclusion in a larger tax package.

That said, there are two areas worth watching. The first is California state action. The state has historically responded to federal incentive gaps with state-level alternatives, and Assembly bills around home hardening tax credits have been discussed (AB 888 was the most recent meaningful one — a grant program, not a credit). A state-level window credit specifically tied to Title 24 over-compliance is a logical policy fit, but nothing concrete is on the table for 2026.

The second is utility programs. PG&E and SMUD adjust their rebate offerings annually based on energy efficiency portfolio targets. If grid stress in California summers continues to drive cooling demand, utility-side incentives for solar heat gain reduction — which windows directly affect — could expand. We see this already in the Sacramento Valley with SMUD's higher-tier rebates for cool roofs and HVAC; windows could follow.

For now, plan around what exists. The federal credit is gone. California programs are real but require active engagement with county OES, your insurance carrier, and your utility. The dollars are smaller and more diffuse than a single federal credit, but they are recurring, which Section 25C never was.

The end of Section 25C changes the math on premium window upgrades, but it does not change the underlying logic of when window replacement is worth it. Failed seals, single-pane windows, drafty frames, and code-required upgrades during permitted remodels are still strong reasons to invest. The federal credit was never the primary driver of the math — it was a $600 nudge on top of a $7,000 to $12,000 decision.

For most Sierra Foothills homeowners, the practical 2026 choice is between three product tiers. Vinyl dual-pane Low-E with argon at $450 to $700 per window installed meets Title 24 and qualifies for FAIR Plan discounts. Fiberglass dual-pane at $700 to $1,000 adds durability, which matters at our elevations where freeze-thaw cycles stress frames. Triple-pane ENERGY STAR Most Efficient at $1,000 to $1,500+ per window delivers maximum efficiency and noise reduction, and remains the right call for homes near I-80 or the rail line.

My honest recommendation: if you have failed double-pane seals, single-pane windows, or a permitted remodel coming up, do the project in 2026 and stack the California incentives that exist. Do not delay hoping the federal credit returns — there is no clear path to that happening on any near-term timeline. If your existing windows are functional double-pane in good shape, spending on attic insulation, a heat pump, or air sealing typically returns more per dollar than upgrading already-decent glass.

We walk through this evaluation on every quote. The right answer depends on your existing windows, your climate zone, your insurance situation, and how long you plan to stay in the home — not on whether the federal government is offering a credit this year.