What are the prevailing wage and apprenticeship requirements for Section 179D?

All laborers and mechanics employed by the taxpayer, contractors, and subcontractors in construction — and, for 179D, alterations and repairs — must be paid at least Davis-Bacon prevailing rates for the locality and classification, and qualified apprentices from registered programs must perform at least 15 percent of total construction labor hours (for construction beginning in 2024 or later), subject to ratio and participation rules. Meeting both multiplies the deduction by five.

Can a prevailing-wage shortfall be cured after the fact?

Yes. Under the final regulations (T.D. 9998), a taxpayer preserves the enhanced amount by paying each underpaid worker the shortfall plus interest at the federal short-term rate plus six points, and paying the IRS a $5,000 penalty per affected worker. Intentional disregard triples the cure payment and doubles the penalty to $10,000. Correction is unavailable only in limited intentional-disregard scenarios.

Do older projects need PWA compliance to get the enhanced 179D deduction?

No. Projects whose construction began before January 29, 2023 — 60 days after Notice 2022-61 was published — are deemed to satisfy the requirements and receive the five-times amounts automatically. Later projects must document compliance from the start of construction; wage records cannot be reconstructed convincingly after completion.

Prevailing wage and apprenticeship rules: the five-times multiplier, briefly

The Inflation Reduction Act's prevailing wage and apprenticeship (PWA) rules are the hinge on which most post-2022 energy incentive math turns. For Section 179D, compliance multiplies the deduction by five — from roughly $0.58–$1.16 per square foot to $2.90–$5.81 (2025, indexed). For multifamily Section 45L, prevailing wage alone lifts the per-unit credit from $500/$1,000 to $2,500/$5,000. Congress priced the base amounts low deliberately: the real incentive was reserved for projects paying union-scale wages. The final regulations, T.D. 9998 (June 2024), govern.

The two requirements

Prevailing wage. Every laborer and mechanic employed in construction — by the taxpayer or any contractor or subcontractor, at any tier — must be paid no less than the Davis-Bacon Act prevailing rate published by the Department of Labor (sam.gov wage determinations) for the work classification and locality, including the fringe component. For 179D, the obligation extends to alterations and repairs for a period after the property is placed in service, a tail that surprises owners. Where no determination covers a classification, the taxpayer must request a supplemental rate from DOL. "Laborers and mechanics" means workers performing manual work; bona fide supervisory, professional, and clerical staff are outside the rule.

Apprenticeship (179D yes; 45L no). Three tests apply: a labor-hours test — qualified apprentices from registered apprenticeship programs must perform at least 15 percent of total construction labor hours (12.5 percent for construction beginning in 2023, 10 percent earlier); a ratio test — apprentice-to-journeyworker ratios of the registered program must be respected each day; and a participation test — each contractor with four or more construction workers must employ at least one apprentice. A good-faith-effort exception excuses shortfalls where the taxpayer requested apprentices from a registered program and was denied or received no response within five business days, with requests renewed at least every 120 days.

Correction and penalties

The regime is enforceable but forgiving, by design. A wage shortfall does not forfeit the multiplier if the taxpayer makes a correction payment — the underpayment plus interest at the federal short-term rate plus six percentage points — to each affected worker, and pays a $5,000 penalty per worker to the IRS. For intentional disregard, the correction payment triples and the penalty doubles to $10,000 per worker. The regulations reward hygiene: penalties are waived for small shortfalls cured promptly (broadly, workers underpaid for limited periods and made whole within 30 days of discovery or before the return claiming the increased amount is filed), and contemporaneous payroll practices — certified-payroll-style records, posted rates, contractual flow-downs — are treated as evidence against intentional disregard. Apprenticeship failures carry a separate penalty of $50 per shortfall hour ($500 if intentional).

The practical lesson from the first exam cycles is that the multiplier is won at contract drafting, not at filing. Taxpayers who imposed PWA flow-down clauses, collected weekly payrolls, and tracked apprentice hours in real time can substantiate the enhanced amount; those who ask the general contractor for records at study time frequently cannot, and the difference is 80 percent of the deduction.

Transition and sunset

Two dates bracket the regime. Construction beginning before January 29, 2023 is deemed compliant — those projects take the five-times amounts with no wage documentation at all. And with 179D terminated for construction beginning after June 30, 2026 and 45L for homes acquired after that date (see planning around the sunsets), PWA compliance for these two provisions is now a matter of maintaining, not creating, compliance programs on in-flight projects — through placed-in-service for the deduction, and through the alteration-and-repair tail thereafter. The PWA framework itself survives in the credits OBBBA left standing, so the recordkeeping muscle transfers.