What is the 25C tax credit limit for installing a qualifying high-efficiency gas furnace?

Under the Section 25C Energy Efficient Home Improvement Credit, installing a qualifying high-efficiency natural gas furnace allows homeowners to claim 30% of the project cost, capped at a maximum tax credit of $600.

HVAC contractors and specifiers navigate stricter efficiency benchmarks under the 2022 Inflation Reduction Act updates, which restructured Section 25C to incentivize high-efficiency condensing furnace replacements. Homeowners replacing aging baseline equipment require verified efficiency data to lower upfront installation costs while meeting current federal targets.

If you only do one thing: Specify a natural gas furnace rated at 97% AFUE or higher to ensure the unit satisfies the ENERGY STAR criteria required for the $600 credit.

• Credit calculation: Taxpayers receive a nonrefundable federal credit equal to 30% of the total equipment and installation cost, subject to the $600 gas furnace cap.
• Efficiency threshold: Natural gas furnaces must achieve an Annual Fuel Utilization Efficiency (AFUE, the measure of seasonal combustion efficiency) rating of at least 97% to qualify.
• Annual aggregate cap: The $600 furnace credit applies against the broader Section 25C annual cap of $1,200 for standard energy property, which renews annually through 2032.
• Eligible property type: The installation must occur in an existing home located in the United States and used as a residence by the taxpayer; commercial properties and new construction builds are excluded.
• Required documentation: Contractors must furnish the customer with an itemized invoice, the AHRI (Air-Conditioning, Heating, and Refrigeration Institute) certificate, and the Manufacturer Certification Statement confirming efficiency ratings.

• Watch out for: Sub-97% AFUE condensing furnaces, because units rated between 90% and 96% AFUE fail the 25C standard even though they exceed minimum regional building codes.
• Watch out for: Stacking multiple standard HVAC improvements that exceed the $1,200 overall annual envelope limit, such as pairing a $600 furnace with a $600 central air conditioning unit in the same tax year.
• Watch out for: Missing local utility rebates, which reduce the total out-of-pocket project expenditure basis prior to calculating the 30% federal tax credit amount.

Check the AHRI directory to confirm model eligibility before equipment procurement, and direct clients to a qualified tax professional regarding IRS Form 5695 filings.