$5.00/sq ft
MAX DEDUCTION
$1.00/sq ft
BASE DEDUCTION
25% Required
ENERGY REDUCTION
Every 3 Years
RECLAIM PERIOD
How It Works
THREE STEPS TO CLAIM §179D
01
Commission an Energy Study
Engage a qualified energy modeling firm to run software analysis (eQUEST, EnergyPlus, or DOE-2) and demonstrate the required energy savings vs. the ASHRAE 90.1 baseline.
02
Obtain Certification + Allocation Letter
A licensed engineer certifies the energy study. For government or nonprofit buildings, obtain a signed allocation letter designating the designer as the deduction recipient.
03
Claim on Tax Return
Claim the deduction on the applicable tax return (Schedule C, Form 1120, Form 1065, etc.) for the tax year the property is placed in service. Document prevailing wage compliance for rates above $1.00/sq ft.
Eligibility
WHO QUALIFIES FOR 179D
Commercial Building Owners
- +Own and operate commercial or industrial buildings
- +Make qualifying energy-efficient improvements
- +Building must be in the United States
- +Can claim deduction on their own tax return
Designers (Post-IRA Allocation)
- +Architects, engineers, contractors
- +Must design qualifying energy systems
- +Nonprofit/gov building allocates deduction to designer
- +Written allocation agreement required
Qualifying Entity Types
- +S-corps, C-corps, LLCs, partnerships
- +Tax-exempt entities (allocate to designers)
- +State and local government buildings
- +Tribal government-owned properties
Qualifying Building Systems
- +Interior lighting systems
- +HVAC and hot water systems
- +Building envelope (walls, roof, windows)
- +All three systems together for maximum deduction
IRA Expansion
Pre-IRA, only private commercial building owners could benefit from 179D. Now, designers working on government schools, hospitals, and nonprofits can receive the deduction directly — representing millions of square feet of previously unavailable opportunity.
Deduction Rates
RATES AND PREVAILING WAGE REQUIREMENTS
The IRA tied higher deduction rates to prevailing wage and apprenticeship requirements. The maximum $5.00/sq ft requires both energy performance and labor compliance.
| Deduction Rate | Standard | Prevailing Wage | Notes |
|---|---|---|---|
| $0.50/sq ft | Minimum (each system) | No | Per qualified system (lighting, HVAC, envelope) |
| $1.00/sq ft | Full without PW | No | 25% energy reduction, no prevailing wage |
| $2.50/sq ft | PW Minimum | Yes | Prevailing wage, partial systems |
| $5.00/sq ft | Maximum | Yes + Apprenticeship | Full 25% reduction, prevailing wage + apprenticeship |
Energy Modeling Required
A qualified software modeling study (using IRS-approved programs like eQUEST, EnergyPlus, or DOE-2) must demonstrate the required 25% energy reduction vs. the ASHRAE 90.1 baseline before the deduction can be claimed.
Claim Process
HOW TO CLAIM 179D
01
Commission an Energy Study
Engage a qualified energy modeling firm to run software analysis and demonstrate the required energy savings vs. ASHRAE 90.1.
02
Obtain Qualified Certification
A qualified individual (licensed engineer or contractor) certifies the energy study results and the qualifying improvements.
03
Secure Allocation Letter (if nonprofit/gov)
For government or nonprofit buildings, obtain a signed allocation letter from the building owner designating the designer as the deduction recipient.
04
Document Prevailing Wage Compliance
If claiming rates above $1.00/sq ft, document that all construction workers were paid prevailing wages and apprenticeship requirements were met.
05
Claim on Tax Return
Claim the deduction on the applicable tax return (Schedule C, Form 1120, Form 1065, etc.) for the tax year the property is placed in service.
Example Calculation
100,000 SQ FT OFFICE BUILDING
// Government school building — designer allocation
Building: 100,000 sq ft
Systems: All 3 (lighting, HVAC, envelope)
Energy reduction: 28% vs ASHRAE 90.1
Prevailing wage: Yes + apprenticeship
Deduction rate: $5.00/sq ft (maximum)
Total deduction: 100,000 × $5.00 = $500,000
Tax value (21%): ~$105,000
* Deduction allocated from the tax-exempt school to the design firm per IRA rules.
CFO Checklist
BEFORE YOU FILE §179D
1. Confirm the building is commercial or industrial and located in the United States — residential is excluded except for multifamily under ZERH (use §45L instead).
2. Commission a qualified energy model using IRS-approved software (eQUEST, EnergyPlus, or DOE-2) demonstrating ≥25% reduction vs. ASHRAE 90.1.
3. For nonprofit or government buildings, execute a written allocation agreement before the tax year closes — the allocation cannot be backdated.
4. Document prevailing wage compliance for every worker on the qualifying systems if you intend to claim rates above $1.00/sq ft.
5. Check the 3-year reclaim window — a building is eligible again once three years have elapsed since the prior 179D claim on the same property.
FAQ
FREQUENTLY ASKED QUESTIONS
Who is eligible for Section 179D?
Commercial building owners and designers (architects, engineers) who make qualifying energy efficiency improvements. Post-IRA, designers working on government, tribal, and nonprofit buildings can now receive an allocated deduction directly from those tax-exempt entities.
What is the maximum 179D deduction per square foot?
The maximum deduction is $5.00 per square foot for buildings meeting the full 25% energy reduction standard with prevailing wage and apprenticeship compliance. Without prevailing wage, the maximum is $1.00/sq ft.
Can nonprofits and government agencies use 179D?
Tax-exempt entities cannot directly use 179D since they have no tax liability. However, the IRA allows them to allocate the 179D deduction to the designer (architect, engineer, or contractor) who designed the energy-efficient systems. This is a major change that opened 179D to a much larger market.
What building systems qualify for 179D?
Three building systems qualify: (1) Interior lighting systems, (2) HVAC and hot water systems, and (3) Building envelope improvements. A partial deduction of $0.50–$1.00/sq ft is available for each system independently.
How often can a building claim 179D?
A building can claim 179D once every three years. If improvements are made across multiple phases, each phase can potentially qualify if three years have elapsed since the prior claim on that building.