The 179D deduction rewards energy-efficient commercial building projects — but the window has a hard edge: the deduction applies to projects that began construction before July 1, 2026. If your project made that cutoff, you can still claim the deduction when the building is placed in service.
Who can claim 179D
Building owners are the most common claimants, but designers of government-owned and certain tax-exempt buildings (architects, engineers, design-build contractors) can also receive an allocated deduction. Warehouses, offices, retail, schools, and municipal buildings are all fair game if the energy targets are met.
What the deduction is worth
The deduction is calculated per square foot and scales with the energy savings achieved and whether prevailing wage and apprenticeship requirements were met. On a large building, it can run well into six figures — which is why it is worth a qualification check even if you are not sure your project qualifies.
The catch: documentation
179D is documentation-heavy. You need an energy model or design review, and certification by a qualified third party. The point of a preliminary screen is to decide whether that effort is worth it for your project before you spend money on it.
Check your project in under a minute
Run our free 179D qualification check — no signup, and your numbers never leave your browser. If it looks promising, request a professional review and we will match you with a specialist.
This article is for preliminary education only and is not tax, legal, or accounting advice.