How the 25C Insulation Tax Credit Works in 2026

What is the 25C insulation tax credit?

Section 25C of the tax code is the Energy Efficient Home Improvement Credit. It is a federal credit for homeowners who make specific efficiency upgrades to an existing home they live in.

Insulation and air sealing are among the qualifying categories, alongside exterior doors, windows, heat pumps, and electrical panel upgrades. Each category has its own rules and its own place under the annual cap.

The credit is worth 30 percent of qualifying costs, up to $1,200 per year across the covered improvement categories. It is nonrefundable, meaning it reduces the tax you owe and does not pay out beyond that.

What insulation work qualifies?

Bulk insulation products and air sealing materials that meet the applicable efficiency criteria. In practice that covers the work most Weld County homeowners are already considering.

• Blown-in cellulose and fiberglass in attics and walls
• Batts and rolls
• Spray foam, open and closed cell
• Rigid board insulation
• Weatherstripping, house wrap, caulk, and expanding foam sealants

That last group matters more than it looks. Attic air sealing materials qualify, and sealing is the step that makes new R-value perform. A combined seal and insulate project puts both material costs under the same credit.

How much money is actually involved?

Work an example. A Greeley attic upgraded to R-49 costs $3,200, and the contractor's invoice shows $1,900 in materials and $1,300 in labor. Thirty percent of the material figure is $570, and that is the credit.

A larger project, say a $6,000 combination of crawl space foam and attic work, can produce enough qualifying material cost to reach the $1,200 annual ceiling. Anything past that ceiling in the same tax year does not add to the credit.

Because the cap resets annually, splitting a large project across two calendar years is a legitimate strategy. Attic this December, crawl space in January, two separate caps.

Want a materials and labor breakdown on your quote? Call (970) 414-2650

What does not qualify?

Installation labor does not qualify for the insulation and air sealing categories. That surprises people, since labor is often half the invoice. Some other 25C categories do include labor, but insulation is not one of them.

Also excluded: work on a new home you have not moved into, work on a property you rent to someone else, and general remodeling that happens to touch insulation. The improvement has to be to an existing home used as a residence.

How do you claim the insulation tax credit?

Four steps, and the first one happens before the work starts.

1. Ask for materials to be itemized. Tell your contractor at quote time that you need the material cost broken out. Retrofitting that detail onto an invoice later is harder than asking up front.
2. Keep the documentation. The invoice, the product data sheets, and any manufacturer certification statement. Store them with your tax records for the year.
3. File Form 5695. Residential Energy Credits, filed with your federal return for the year the work was completed and placed in service.
4. Carry the result to Form 1040. The credit reduces your tax liability directly.

Can you combine the credit with an Xcel Energy rebate?

Usually yes, and Colorado homeowners often do. A utility rebate and a federal credit come from different sources, so most people claim both on the same project.

One accounting detail: a rebate that reduces the purchase price generally reduces the cost basis you calculate the credit from. If Xcel sends $400 back on a $3,200 job, the credit is figured on the reduced amount. Walk through the utility side in the Xcel insulation rebate guide.

Verify the current year rules before you budget

Federal energy credit rules have been amended more than once in recent years, including changes to which years the credit applies to. Terms, caps, and end dates can all move.

Before you count a credit into a project budget, read the current IRS page for the Energy Efficient Home Improvement Credit and confirm it applies to the tax year your work is completed. A contractor cannot give tax advice, and neither can this page. Your tax professional can.

For what the work itself costs before any credit, the attic insulation cost guide and the spray foam cost guide carry current Northern Colorado ranges.

Insulation tax credit questions

Credit terms referenced from the IRS Energy Efficient Home Improvement Credit page: irs.gov. Qualifying product criteria are listed at energystar.gov. This article is general information, not tax advice.