The tax deduction that turns a good LED project into a great one
Section 179D of the Internal Revenue Code allows building owners to deduct up to $5.81 per square foot (2025 rates, with prevailing wage) for installing energy-efficient lighting, HVAC, or envelope improvements in commercial buildings. For a 50,000 sq ft warehouse, that is potentially a $290,000+ tax deduction on top of any utility rebates and energy savings the project already delivers. The deduction has been available since 2006, was expanded significantly by the Inflation Reduction Act in 2022, and was terminated for projects beginning construction after June 30, 2026 by the One Big Beautiful Bill Act signed in July 2025. The window is closing.
This article is for informational purposes only. Jarvis Lighting is not a tax advisory firm. The 179D deduction involves tax law that changes frequently and depends on project-specific circumstances. Always consult a qualified tax advisor or CPA before making decisions based on 179D. The information below reflects the law as of March 2026 and may change with subsequent IRS guidance or legislation.
How 179D works: the short version
A building owner (or in some cases, a designer) installs energy-efficient improvements in a commercial building. The improvements reduce the building's energy use compared to a baseline ASHRAE 90.1 standard. A qualified professional (licensed architect or engineer) certifies that the improvements meet the energy savings threshold. The building owner claims a tax deduction on IRS Form 7205 equal to the applicable rate per square foot, up to the cost of the improvements.
The qualifying building systems are: interior lighting, HVAC, hot water (service water heating), and building envelope. A project can include one system or all four. Interior lighting upgrades (fluorescent-to-LED retrofits, HID-to-LED conversions, controls upgrades) are one of the most straightforward paths to qualification because LED technology routinely achieves the required energy savings thresholds.
How much is the deduction worth?
| Tax year | Base rate (no prevailing wage) | Prevailing wage + apprenticeship rate | Energy savings threshold |
|---|---|---|---|
| 2025 | $0.58/sq ft (at 25% savings) to $1.16/sq ft (at 54% savings) | $2.90/sq ft (at 25%) to $5.81/sq ft (at 54%) | 25% minimum. Increases $0.02/sq ft per percentage point above 25%. |
| 2026 | $0.59/sq ft to $1.19/sq ft | $2.97/sq ft to $5.94/sq ft | Same structure, inflation-adjusted. |
Source: IRS Form 7205 Instructions (December 2025 revision) and 26 U.S.C. Section 179D(g) inflation adjustment provisions. The prevailing wage multiplier is 5x the base rate per the Inflation Reduction Act. Rates are indexed annually for inflation.
The prevailing wage and apprenticeship bonus is significant: 5x the base deduction. A project that qualifies at the base rate of $1.16/sq ft earns $5.81/sq ft with prevailing wage. For contractors already paying prevailing wages (union shops, government contracts, many institutional projects), this is not an additional cost; it is a multiplier on a requirement they already meet.
Worked example: 50,000 sq ft warehouse LED retrofit
The project
Given: A 50,000 sq ft warehouse replacing 400W metal halide fixtures with 150W LED high bays. The lighting upgrade reduces whole-building energy use by 30% (lighting is a major component in warehouse energy). Project meets prevailing wage requirements. Tax year 2025.
Prevailing wage rate at 30% savings:
$2.90 base + ($0.10 x 5 percentage points above 25%) = $3.40/sq ft
Deduction: 50,000 sq ft x $3.40 = $170,000
Cap: deduction cannot exceed the cost of the improvements.
Project cost (fixtures + installation): $175,000
Deduction allowed: $170,000 (under the cap)
Stacking with utility rebates
NLC incentive (50 fixtures x $30): $1,500
179D tax deduction: $170,000
Annual energy savings: $8,710/year (from the LED vs MH guide)
Year 1 financial impact:
Project cost: $175,000
Minus rebates: -$6,500
Minus 179D deduction value (at 24% tax rate): -$40,800
Net out-of-pocket after year 1: $127,700
Ongoing savings: $8,710/year
This is a simplified illustration. The actual 179D deduction depends on the whole-building energy model, not just the lighting component. The deduction amount, tax rate impact, and interaction with depreciation depend on the building owner's specific tax situation. Consult a tax advisor and a qualified 179D certification professional for project-specific analysis.
The June 30, 2026 deadline: what it means and how to meet it
The One Big Beautiful Bill Act (Public Law 119-21, signed July 4, 2025) added a termination provision to Section 179D: the deduction does not apply to property whose construction begins after June 30, 2026.
"Begins construction" is defined by the IRS using two tests (the taxpayer can use either one):
| Test | What it requires | Practical meaning for a lighting project |
|---|---|---|
| Physical Work Test | Significant physical work of a significant nature begins before the deadline. | Ordering fixtures and having them delivered may not qualify. Actual installation work (removing old fixtures, pulling wire, mounting new fixtures) before June 30, 2026 should qualify. Consult a tax advisor for the specific threshold. |
| 5% Safe Harbor | At least 5% of the total project cost is paid or incurred before the deadline. | For a $175,000 project, that is $8,750. Placing a deposit or making a down payment of at least 5% before June 30, 2026 should meet this test. Equipment orders with binding contracts may also qualify. |
Both tests also require a Continuity Requirement: the project must make continuous efforts toward completion after the construction start date. A project that starts before the deadline but stalls for years may not qualify.
The deadline is not "placed in service by June 30, 2026." It is "construction begins by June 30, 2026." The project does not have to be completed by that date. It just has to demonstrably start. For building owners considering an LED upgrade in 2026 or 2027, starting the project (even a partial phase) before the deadline preserves eligibility for the deduction on the entire project scope.
Who can claim it
| Building ownership | Who claims the deduction |
|---|---|
| Privately owned commercial building | The building owner who pays for and depreciates the improvements. |
| Tenant improvements | The tenant, if the tenant pays for the improvements and depreciates them. |
| Government-owned building (federal, state, local, tribal) | The designer of the energy-efficient property (architect, engineer, lighting designer) receives an allocated deduction from the government entity. |
| Tax-exempt organization (nonprofit hospital, university, church, museum) | The designer, via allocated deduction. This was expanded by the Inflation Reduction Act to include a wider range of tax-exempt entities. |
| REIT (Real Estate Investment Trust) | The REIT. This was added by the Inflation Reduction Act. |
The designer allocation for government and tax-exempt buildings is a significant opportunity for architects, engineers, ESCOs, and lighting design firms. If you design the lighting for a public school, a government office building, or a nonprofit hospital, the building owner cannot use the deduction (they have no tax liability), but you can.
How LED lighting upgrades qualify
Interior lighting is one of the four qualifying building systems. To qualify for 179D, the lighting upgrade must be part of a project that reduces the building's total annual energy and power costs by at least 25% compared to the applicable ASHRAE 90.1 reference standard. The energy savings are calculated using qualified computer software (whole-building energy modeling).
LED retrofits are strong candidates because they routinely achieve 50-70% wattage reductions on the lighting load. In buildings where lighting is a large share of total energy (warehouses, retail, schools), a lighting-only upgrade can push the whole-building savings above the 25% threshold. In buildings where HVAC dominates (offices, hospitals), the lighting upgrade may need to be combined with HVAC or envelope improvements to reach 25%.
Additionally, the reduced heat output from LED fixtures lowers the HVAC cooling load, which adds to the whole-building energy savings in the model. This secondary effect can push a borderline project over the 25% threshold.
For the technical details of LED retrofit paths and energy savings calculations, see the LED vs. Metal Halide comparison, the fluorescent retrofit guide, and the utility rebates guide (which covers how 179D stacks with prescriptive rebates).
Frequently asked questions
What is the 179D tax deduction?
A federal tax deduction under IRC Section 179D for installing energy-efficient lighting, HVAC, hot water, or envelope improvements in commercial buildings. The deduction is based on the building's square footage and the percentage of energy savings achieved. It was expanded by the Inflation Reduction Act of 2022 and terminated for projects starting construction after June 30, 2026.
How much is it worth?
For 2025: up to $1.16/sq ft at the base rate, or up to $5.81/sq ft with prevailing wage and apprenticeship compliance. For a 50,000 sq ft building at the prevailing wage rate with 30% savings, the deduction is approximately $170,000. The deduction is capped at the cost of the improvements and is reduced by any 179D deductions claimed for the same building in the prior 3-4 years.
Do LED lighting upgrades qualify?
Yes. Interior lighting is a qualifying system. The project must reduce whole-building energy use by at least 25% versus ASHRAE 90.1. LED retrofits replacing fluorescent or HID lighting routinely achieve 50-70% lighting wattage reductions, which often pushes the whole-building savings above the threshold, especially in lighting-intensive buildings like warehouses and schools.
When does it expire?
The One Big Beautiful Bill Act terminated 179D for projects beginning construction after June 30, 2026. "Beginning construction" can be met through the Physical Work Test (actual installation begins) or the 5% Safe Harbor (at least 5% of project cost is paid or incurred). A Continuity Requirement also applies. Consult a tax advisor for your specific project timeline.
Can I combine 179D with utility rebates?
Yes. The 179D deduction and utility rebates are separate programs with separate requirements. A project can receive both. The deduction is capped at the cost of the improvements, and the rebate does not reduce the eligible cost basis for 179D. Together, rebates and 179D can offset 30-50% or more of total project cost. See the rebate guide for utility program details.
Who can claim it for government or nonprofit buildings?
The designer of the energy-efficient property. If you are the architect, engineer, ESCO, or lighting designer who designed the improvements for a government, tribal, or tax-exempt building (school, hospital, nonprofit), the building owner can allocate the deduction to you. This designer allocation was expanded by the Inflation Reduction Act and is available for a broader range of tax-exempt entities than before.
