Methodology and data sources
Trust comes from showing your work. This page lays out where the data comes from, how often it's refreshed, and how we verify accuracy before publishing.
Last reviewed:
Data source hierarchy
We rank sources by authority. Higher-tier sources override lower-tier sources when there's a conflict. If Rewiring America shows a federal credit as active but the IRS guidance says it's expired, we go with the IRS.
IRS / U.S. Treasury
The primary authority for all federal tax credit claims. We rely on official IRS guidance, Treasury fact sheets, and enacted legislation to determine credit eligibility and amounts.
Rewiring America API
A database of federal, state, utility, and local incentive programs. The calculator queries the API in real time and returns programs matching the user's location and upgrade type.
OpenEI (U.S. DOE)
The U.S. Department of Energy's utility rate database. We use it to show average residential electricity rates by state and utility territory.
EnergySage
A solar marketplace providing real installation cost data, installer ratings, and city-level pricing. We use it for average solar costs and installer listings on city pages.
Zippopotam.us
A free ZIP code resolution API. We use it to determine the user's city, state, and county from their ZIP code input.
Current federal program status
The following federal programs are tracked in our data layer. Status is determined by IRS guidance and enacted legislation, not by third-party databases.
Residential Clean Energy Credit (Section 25D)
Previously provided a 30% tax credit for solar panels, battery storage, geothermal heat pumps, and other residential clean energy installations.
Energy Efficient Home Improvement Credit (Section 25C)
Previously provided up to $3,200/year for energy-efficient home improvements including heat pumps, insulation, windows, doors, and energy audits.
Alternative Fuel Vehicle Refueling Property Credit (Section 30C)
Previously provided up to 30% of costs (max $1,000 residential) for EV charger installations in eligible census tracts.
Home Energy Rebates (HEEHRA / HOMES)
The DOE Home Energy Rebates program includes two components: the HOMES rebate (whole-home energy savings) and the HEAR rebate (high-efficiency electric home appliances). Funding was allocated to states and territories, and status varies.
Editorial standards
No unverified federal claims
We never claim a federal credit is active unless we can cite current IRS guidance or enacted law. If a program's status is ambiguous, we label it 'watchlist' rather than 'active'.
Source attribution
Every data point on the site is traceable to one of our data sources. Source badges (IRS, DOE, Rewiring America, EnergySage) appear on all pages.
Freshness indicators
Every page displays a 'last verified' date. State and city pages use ISR with 7-day revalidation. Program data from Rewiring America is fetched in real time.
Estimates, not guarantees
All savings figures are estimates based on available data. We show disclaimers on every page and tell users to verify with their tax professional.
How we verify data
Step 1: primary source check. When legislation changes (the One Big Beautiful Bill Act of 2025, for example), we go directly to the enrolled bill text and IRS guidance to figure out the impact on each tracked program.
Step 2: cross-reference APIs. We compare our determination against Rewiring America's API output. When the two disagree, the higher-tier source (IRS or legislation) wins, and we note the override.
Step 3: update the data layer. Changes flow into our federal programs data layer with a new verification date and a source URL. Every page that references the affected program reflects the new status automatically.
Step 4: publish a changelog entry. We record the change on our Updates page so users can see what changed and when.
Spot something wrong?
If you find incorrect data on the site, tell us. We investigate within 24 hours and update the data layer when something needs to change.