45L Tax Credit Explained: Builder Credits Up to $5,000/Unit (2026)

The Section 45L New Energy Efficient Home Tax Credit is one of the most powerful credits available to builders and developers in the United States. This page explains the credit, the current 2026 deadline, the certification process, and how HECS USA helps builders claim the credit.

What 45L Is

Section 45L of the Internal Revenue Code provides a federal income tax credit for contractors (builders) who construct or substantially reconstruct qualified new energy-efficient homes. The credit amount depends on the home’s energy performance and type:

  • $2,500 per home meeting ENERGY STAR standards
  • $5,000 per home meeting Zero Energy Ready Home (ZERH) standards
  • $5,000 per multifamily unit meeting prevailing wage + apprenticeship standards

The credit is non-refundable but can be carried forward to future tax years. There is no annual cap for individual credits, but the program is open to everyone from small custom builders to large production homebuilders.

Current Status: The Inflation Reduction Act Extension

The Inflation Reduction Act of 2022 extended the 45L credit through December 31, 2032, but with two distinct rule sets:

  1. 2023 through June 30, 2026 — applies to homes acquired by a buyer between January 1, 2023 and June 30, 2026. Current relaxed rules apply: ENERGY STAR or better is sufficient.
  2. After July 1, 2026 — homes must meet new DOE Zero Energy Ready Home program rules AND prevailing wage / apprenticeship requirements (for multifamily, apartments, and >=4 homes in a year).

This is the critical deadline: if your project closes or leases after July 1, 2026, the relaxed rules no longer apply. You will need to either obtain ZERH certification, meet prevailing-wage/apprenticeship rules, or work with a qualified energy consultant to verify compliance.

How a Home Qualifies for 45L

The home must satisfy one of two certification paths, both verified by a HERS Rater:

Path 1: ENERGY STAR Certified Home (Low-Rise Residential)

The home must be certified to the current ENERGY STAR Certified Homes program version (Version 3.x). This requires:

  • A completed HERS rating (or Energy Rating Index) of the home
  • Blower-door test (air leakage ≤ target)
  • Duct-leakage test (total ≤ target to outside)
  • HVAC startup and combustion analysis
  • Water-management inspections and a written thermal envelope checklist

Path 2: DOE Zero Energy Ready Home (ZERH)

Tighter envelope, more efficient HVAC, and PV-readiness. HECS USA guides builders through both ENERGY STAR and ZERH certification, depending on which makes sense for your project.

The Role of a HERS Rater in 45L

For 45L purposes, a qualified third-party HERS Rater must provide verification. The IRS accepts only HERS-rated homes where the HERS Rater is RESNET-accredited, the home meets ENERGY STAR program requirements, and the documentation is retained by the builder for 7 years.

HECS USA is a RESNET-accredited HERS Rating Provider. Our 45L workflow covers:

  1. Plan review — energy modeling and projected HERS Index to confirm the design qualifies before construction starts.
  2. Pre-drywall inspection — verifies insulation, framing, duct rough-in, and window specs.
  3. Final inspection — verifies blower door, duct leakage, HVAC performance, and ENERGY STAR or ZERH checklist.
  4. ENERGY STAR/ZERH certificate — the official documentation the IRS requires.
  5. Builder-facing record retention — HECS retains the inspection record for 7 years (per IRS requirements) and provides copies on demand.

Frequently Asked Questions

Who is eligible to claim the 45L credit?

The contractor that built the home and that owns the home at the time of sale or lease. For custom homes sold to a buyer, the custom builder. For multifamily rentals, the developer.

How much can a builder save with 45L?

A builder constructing 100 ENERGY STAR-certified homes per year can claim $250,000 in federal tax credits ($2,500/home). Multifamily developers qualifying for the bonus (ZERH or apprenticeship/prevailing wage) can claim up to $500,000.

What if the home does not meet 45L requirements?

The credit is not available. There is no partial credit. The home either meets the full ENERGY STAR or ZERH criteria or it does not qualify.

Can I claim 45L retroactively?

No. The credit is claimed on the tax return for the year the home is first acquired by a buyer or first used by a lessee. The home must be certified BEFORE sale or lease.

Get 45L Certification for Your Project

HECS USA provides 45L HERS ratings, ENERGY STAR certification, blower door testing, duct leakage testing, and ZERH verification for builders across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. Whether you are building 5 custom homes or 500 multifamily units, we have a 45L workflow that fits. Call (859) 983-7382 or request a 45L quote online.