The Energy Efficient Home Improvement Credit (25C), Explained

Put a $12,000 heat pump in your house this year and the IRS owes you $2,000 back at tax time. That’s the Energy Efficient Home Improvement Credit, Section 25C of the tax code, and heat pumps are only one line on its menu. Insulation counts. So do windows, exterior doors, water heaters, electrical panels, and the energy audit that tells you which upgrade to do first.

Most homeowners claim less than they could, usually because the caps confuse them. Fair enough. There are two separate annual buckets, per-item limits inside one of them, and a labor rule that treats a heat pump differently from a window. This guide walks through all of it, with the numbers that apply to 2025 and 2026 projects. If you want an estimate before reading 1,500 words of tax rules, our OBBB calculator does the math in about a minute.

What the credit pays

The base rate is 30% of what you spent on a qualifying improvement. The credit comes straight off your tax bill, unlike a deduction, which only shrinks the income you’re taxed on. A $1,000 deduction saves a typical filer around $220. A $1,000 credit saves $1,000.

A few ground rules before the caps.

The credit applies to the year the improvement was placed in service, meaning installed and working. Buy windows in December, install them in January, and they belong to the January tax year.

It resets every year. There is no lifetime limit anymore. The old $500 lifetime cap died at the end of 2022, and I still get emails from readers who skipped upgrades because a contractor quoted them the pre-2023 rule.

It only applies to an existing home you live in. New construction is out, and so are rentals you own but don’t occupy.

Energy efficient home improvement credit limits for 2025 and 2026

Everything except the heat pump row shares one general annual cap: $1,600 under the OBBB rules that took effect in 2025, up from $1,200 in 2024. The heat pump bucket sits on top of that. Max out both and you’re at $3,600 in a single year.

How the two buckets actually interact

A worked example, since this is where people get the number wrong.

Say you replace your windows for $8,000, add attic insulation for $3,000, and install a $12,000 cold-climate heat pump, all in the same year.

Windows: 30% of $8,000 is $2,400, but the window cap cuts that to $600. Insulation: 30% of $3,000 is $900, no item cap. That’s $1,500 heading into the general bucket, and the $1,600 cap lets all of it through. The heat pump earns 30% of $12,000, which is $3,600, trimmed to $2,000 by its own bucket.

Total credit: $4,100… no, $3,500. I did that on purpose, because it’s the exact arithmetic slip I see in reader emails. $600 plus $900 plus $2,000 is $3,500. The 30% figures before capping are noise. Only the capped amounts add up.

Had you done the same three projects in 2024, the general bucket would have stopped at $1,200 and the windows plus insulation would have lost $300. That gap is the OBBB change in action, and it’s why sequencing matters. The cap resets each January. A homeowner who does windows in November and insulation in February claims against two separate annual caps instead of cramming both under one.

What qualifies for the energy efficient home improvement credit

Heat pumps and biomass stoves

The $2,000 bucket. Air-source heat pumps need to meet CEE efficiency tiers for your region, which your installer should confirm in writing before you sign anything. Wood and pellet stoves qualify at 75% HHV efficiency or better. Installation labor counts toward the cost basis here, which matters because labor is often a third of the invoice. Weighing a heat pump against a gas furnace? The credit gap alone ($2,000 vs $600) changes that math, and we’ve run the full comparison separately.

Windows, skylights, and exterior doors

Windows need Energy Star Most Efficient certification. Regular Energy Star is one tier short. Doors need standard Energy Star for your climate zone. One gotcha, though. Labor does not count for this category. The credit runs on product cost only, so a $700 installed window with a $350 sticker price earns 30% of $350.

Garage doors come up constantly in my inbox. They don’t qualify. The rule covers doors between conditioned living space and the outside, and a garage is neither.

Insulation and air sealing

Materials only, labor excluded, same as windows. Batts, blown-in, spray foam, rigid board, caulk, weatherstripping, house wrap. All of it qualifies with no per-item cap, which makes insulation the quiet workhorse of the general bucket. A $4,000 attic job earns $1,200 by itself, and the insulation credit guide covers the materials rules and the DIY advantage.

Furnaces, ACs, boilers, and conventional water heaters

Each capped at $600, each with its own efficiency floor (AFUE for furnaces, SEER2 for central AC). Labor counts for these. A tankless gas water heater qualifies if it hits the Energy Star spec.

Electrical panels

A 200-amp panel upgrade earns up to $600, but only when it’s installed to enable other qualifying work, like a heat pump that your old 100-amp panel couldn’t feed. Since 2025, a panel upgraded for EV charger readiness qualifies even if the charger comes later.

Home energy audits

30% up to $250, raised from $150 by OBBB. The audit needs a certified auditor and a written report. Cheap, and it tells you which of the upgrades above will actually move your bills. If your budget is real money, spend the first $400 here.

The QM code (QMID) requirement for 2025 returns

Starting with 2025 installations, qualifying products must come from a registered Qualified Manufacturer, and your tax return has to include that manufacturer’s PIN for the specific product. Searches for “QMID” spiked all spring, so plenty of people are hitting this rule for the first time at filing.

Get the code from your invoice, the product box, or the manufacturer’s website, and save it with your records the week of the install. Hunting for a PIN eleven months later, for a water heater whose brand you half remember, is misery I’d like you to avoid.

Stacking with state and utility rebates

You can usually claim both. OBBB settled a long-running ambiguity here: state and utility rebates no longer reduce your federal credit basis unless the rebate money itself came from a federal program. Pair a $2,000 state heat pump rebate with the full federal $2,000 and your net install cost drops fast. The interaction rules per program are in our OBBB FAQ.

How to claim the energy tax credit on Form 5695

Form 5695, Part II, filed with your return for the year the work was placed in service. You don’t send receipts in, but you keep them, along with the certification statements and QM codes, for at least three years.

One planning note that catches people. The credit is nonrefundable and 25C has no carryover. If your total tax for the year is $1,400, a $3,500 credit gets you $1,400 and the remaining $2,100 evaporates. Retirees and low-income filers should check their expected tax liability before scheduling a big install year. Sometimes splitting the work across two Decembers rescues thousands of dollars.

Frequently asked questions

Is the credit refundable?

No. It reduces your tax to zero at best, and unused credit does not carry forward to next year. That second part separates 25C from the solar-focused 25D credit, which does carry over. More in the refundability guide.

Is there an income limit?

No income limit in either direction. A filer with $40,000 of income and one with $900,000 face the same caps. Your tax liability is the only practical ceiling, and the income limits breakdown covers every credit’s rules.

Can I claim it for a rental property I own?

Not for a rental you don’t live in. Live in part of the building and the shared-use rules get friendlier. Renters who pay for qualifying improvements to their own residence can claim the credit, which surprises people. The rental property guide maps every scenario.

Do smart thermostats or appliances qualify?

None of those qualify. The appliance-shaped exception is the heat pump water heater, which sits in the $2,000 bucket.

How late can I claim a missed year?

Amend with Form 1040-X, generally within three years of the original filing date. A 2024 install claimed late still uses 2024 caps.

Run your numbers first

Before you book anything, check your expected tax liability, sequence big projects across cap years, collect QM codes at install time, and lead with an audit if you’re unsure where to start. Our OBBB calculator compares your project list against both the 2024 and current rules, and the master guide to energy tax credits covers how 25C fits alongside the solar credit and the EV charger credit.