The Section 45L energy-efficient home credit sunsets for projects placed in service after June 30, 2026 — certification work must start months earlier.
Section 45L of the Internal Revenue Code awards up to $2,500 per dwelling for builders meeting ENERGY STAR v3.1 thresholds, and up to $5,000 per dwelling for homes meeting DOE Zero Energy Ready Home (ZERH) requirements. The credit applies to new construction and substantial rehabilitation of single-family, multifamily, and manufactured housing units. For multifamily projects with 20+ units, a single certification package covering the entire building can yield six-figure credit totals — but only when every dwelling unit is independently verified.
The critical compliance gap HECS encounters on Kentucky and Indiana multifamily projects: the certification must be issued by a RESNET-certified HERS Rater before the building is placed in service. Once the certificate of occupancy issues, the rater cannot retroactively certify the home. Builders who wait until May 2026 to engage a rater on a June-completion project are already late.
| Certification Path | Per-Unit Credit | Rater Credential Required | Energy Threshold |
|---|---|---|---|
| ENERGY STAR v3.1 | $2,500 | RESNET HERS Rater | ENERGY STAR v3.1 checklist |
| DOE Zero Energy Ready Home | $5,000 | RESNET HERS Rater | ZERH v1.0 + ENERGY STAR prerequisite |
| NGBS Green Certified (Green +) | $2,500 (qualified) | NGBS Verifier | NGBS-2023 energy efficiency tier |
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Call (859) 983-7382 Get a QuoteHECS has seen credit claims disallowed when the certification package lacks one of three elements: the rater's signed ENERGY STAR or ZERH checklist, the field-verified HERS Index score, and the dated blower door test report. The blower door test must show ACH50 values meeting the program threshold — HECS measures and records these using calibrated equipment per RESNET Standard 380. Duct leakage testing per RESNET Standard 380 or ACCA Manual D protocols must accompany the airtightness results on projects where ductwork is located outside the thermal envelope.
For multifamily projects in Ohio and Tennessee, HECS also documents whole-building air leakage per ASHRAE 90.1 Section 5.5.3 when the project elects the 90.1 path over ENERGY STAR. The documentation stack HECS delivers to builders includes the rater registration, the energy modeling file, the field test results, and a transmittal letter tying each deliverable to the applicable program checklist. Builders retain these records for at least three years post-claim, per IRS guidance.
HECS verifies the building enclosure, HVAC system performance, and lighting package against the certification path selected. Air leakage testing uses a calibrated blower door; duct leakage uses a Duct Blaster or equivalent per RESNET 380. For ZERH pathway projects, HECS additionally confirms the solar-ready provisions, hot water distribution efficiencies, and high-efficacy lighting fractions required by DOE ZERH v1.0.
The Section 45L credit expires for dwelling units placed in service after June 30, 2026. Projects breaking ground in early 2026 with a 12-month build cycle will not meet the deadline. HECS recommends builders run certification feasibility against the project schedule now — pre-drywall inspections, final blower door tests, and rater sign-off each consume calendar weeks that compress when stacked against utility hookups and certificate of occupancy issuance.
The penalty for a missed deadline is straightforward: zero credit. There is no partial proration, no extension, and no transition relief for projects in mid-construction. A 40-unit multifamily project in Lexington or Nashville that misses the deadline forfeits $100,000 to $200,000 in federal tax credits. HECS has observed builders discover this gap only during year-end tax preparation, when no corrective action is possible.
HECS provides ENERGY STAR Multifamily Reviewer, RESNET HERS Rater, and NGBS Green Certified Verifier services for projects in Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. For a scope call on a 45L-eligible project: (859) 983-7382 or hecsusa.com/contact/. See hecsusa.com/services/ for the full certification stack.
Builders weighing ENERGY STAR v3.1 against DOE ZERH should map both against ASHRAE 90.1-2019 Appendix RC, which ZERH references for its baseline. ENERGY STAR v3.1 (Revision 12) covers single-family and multifamily under separate checklists, each with mandatory items and performance targets. NGBS-2023 Chapter 7 (Energy Efficiency) provides a third path with documented compliance through the NGBS Verifier — a credential HECS holds.
For projects pursuing 45L alongside FORTIFIED Home 2025 (relevant in Tennessee and coastal-adjacent markets), the FORTIFIED roof and wall evaluations layer onto the energy certification rather than substitute for it. HECS holds the IBHS FORTIFIED Home Evaluator credential and can bundle both certifications into a single site visit when geography permits. See HECS FORTIFIED Roof Evaluation Nashville for a Tennessee-specific scope example.
The most frequent deficiency on 45L submissions: HVAC equipment nameplates that don't match the ENERGY STAR certified products list (CPL) at the time of installation. Manufacturers periodically update CPL entries, and a furnace or heat pump replaced mid-construction may not hold the same efficiency rating as the originally specified unit. HECS cross-checks installed equipment against the CPL during the pre-final inspection, before the rater signs the checklist. Builders who install substituted units without rerunning the energy model risk having the certification invalidated.
Can a builder claim 45L on a project that received its certificate of occupancy in May 2026, or does the unit need to be placed in service by June 30?
The dwelling unit must be "placed in service" — generally interpreted as the date a certificate of occupancy issues or the unit is legally available for occupancy, whichever applies under local code — by June 30, 2026. HECS recommends builders treat the C/O date as the controlling deadline and back-calculate the certification timeline from there.
Does the 45L certification require third-party field testing, or can a builder self-certify?
Section 45L requires certification by a RESNET-accredited provider using a certified HERS Rater or an equivalent ENERGY STAR/ZERH verification pathway. Self-certification by the builder does not meet the statutory requirement. HECS provides this third-party verification for projects across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri.
What happens if a project fails the blower door test on the first attempt?
HECS typically identifies air leakage paths during diagnostic inspection, and the builder's insulation subcontractor performs remediation before a retest. The retest is scheduled within the same site visit window when possible. HECS documents both attempts, with the passing result becoming the certification record. Projects targeting ZERH thresholds have tighter ACH50 limits, so early rough-in inspection is critical.
HECS provides 45L Tax Credit Certification, ENERGY STAR Multifamily Reviewer services, blower door testing, duct leakage testing, and HERS Rater verification for projects across Kentucky, Indiana, Ohio, Tennessee, Illinois, and Missouri. To scope a 45L certification, call (859) 983-7382 or email [email protected]. Project intake begins at hecsusa.com/contact/, and the full service catalog is at hecsusa.com/services/. HECS also serves Louisville KY, Lexington KY, Cincinnati OH, Indianapolis IN, Nashville TN, St. Louis MO, and Evansville IN directly — local city pages detail state-specific certification timelines and code references relevant to each market.
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