Energy Tax Credit Calculator.

Every cap in one place: the $600 window limit, the $1,600 general bucket, the $2,000 heat pump bucket, and the uncapped 30% for solar and batteries. Add your expected tax and it runs the credit limit worksheet too, showing what your liability actually lets you claim this year, what carries forward, and what would be lost. The rules behind each number are in the 25C guide and the 25D guide.

Efficiency projects (25C)

Windows and skylights ($)Product cost only, labor excluded. Credit caps at $600.Exterior doors ($)Product cost only. $250 per door, $500 total.Insulation and air sealing, materials ($)No per-item cap. DIY installs claim full materials cost.Water heater, furnace, or central AC ($)Installed cost. Capped at $600 per item.Electrical panel upgrade ($)Must enable other qualifying equipment. Cap $600.Home energy audit ($)Certified auditor with written report. Cap $250.Heat pump or biomass stove ($)Installed cost, labor included. Separate $2,000 bucket.

Clean energy (25D)

Solar ($)Full installed cost. 30% with no cap.Battery storage ($)3 kWh minimum. Standalone qualifies from 2025.Geothermal ($)

Your credit limit

Expected total tax, line 22 ($)Last year's 1040 line 22 is a good estimate. Leave blank to skip the ceiling.Other nonrefundable credits ($)Child tax credit, EV credit, and similar. They come out of the ceiling first.