TL;DR: Section 179D offers up to $5.81 per square foot in tax deductions for energy-efficient commercial buildings. The program has been around since 2006, was made permanent in 2020, and works retroactively. Most building owners never hear about it because CPAs focus on compliance, not proactive strategy. The One Big Beautiful Bill Act set a hard deadline of June 30, 2026 for new projects.
Core Facts:
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Section 179D provides deductions from $0.50 to $5.81 per square foot for qualifying energy-efficient buildings
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Buildings over 40,000 square feet typically qualify for new construction or major renovations
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Tax-exempt property owners can allocate the deduction to designers, architects, or engineers
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The deduction works retroactively and stacks with cost segregation studies
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Projects must begin construction by June 30, 2026 to qualify
Brian Broussard has spent years helping building owners unlock six-figure deductions they didn’t know existed. Not because the tax code changed recently. Not because some new loophole opened up. Section 179D has been sitting in the tax code since 2006, and most commercial property owners have never heard of it.
Their CPAs haven’t mentioned it either.
David Wiener sat down with Brian to unpack why this deduction remains invisible to the people who need it most, what’s changing under the Big Beautiful Bill, and why June 30, 2026 matters if you own or design commercial buildings.
What Is Section 179D?
Section 179D is a federal tax deduction for commercial buildings that incorporate energy-efficient systems. HVAC, lighting, building envelope, and water heating technologies that meet specific performance standards qualify.
The deduction reaches up to $5.81 per square foot. For a 100,000-square-foot building, that translates to $581,000 in potential deductions.
The program applies to new construction and renovations. Buildings become eligible again every three years for private properties and every four years for tax-exempt facilities. If you didn’t claim the deduction when the building was placed in service, you still have time to go back and claim it retroactively using Form 3115.
This isn’t some obscure provision buried in a footnote. The program has been in effect since 2006 and became permanent in 2020. When David asks building owners if they’ve heard of it, the most common response is straightforward: “What is 179D?”
Bottom line: Section 179D has been available for nearly two decades, applies broadly to commercial buildings, and works retroactively. Most property owners still don’t know it exists.
Why Building Owners Don’t Hear About 179D
The gap isn’t a knowledge problem on the building owner’s side. The issue is systemic, rooted in how tax services work.
Most CPAs operate in tax preparation mode, not tax strategy mode. They file what you give them. They ensure compliance. They get your return submitted on time. Proactively identifying deductions like 179D requires a different approach entirely.
David has built his entire practice around this distinction. “Many tax professionals only do tax preparation, not tax strategy,” he explains. “A preparer won’t necessarily be aware, or well versed, in 179D. That’s one of the reasons I started The Tax Strategy Playbook Podcast.”
There’s another layer. Even when CPAs know about 179D, many clients don’t realize the benefit of tax strategy or don’t want to pay for it. The incentive structure doesn’t reward proactive planning. It rewards efficient compliance.
So the deduction sits there. Available. Substantial. Completely unused.
Key insight: The primary barrier to claiming 179D isn’t complexity or eligibility. It’s the structural divide between tax preparation and tax strategy.
Which Buildings Qualify for 179D?
David’s pattern recognition is straightforward. If you own a commercial building over 40,000 square feet, explore this. If you own a residential property over four stories with similar square footage, same thing.
For new construction, those are automatic candidates. For renovations, the question shifts to what you upgraded. Did you touch the building envelope? Replace HVAC systems? Upgrade lighting? If yes, 179D applies.
There are always exceptions, but those criteria cover the majority of qualifying projects.
Here’s where things get interesting: if the building owner doesn’t pay federal tax, they allocate the deduction to the designer, architect, or engineer through a simple allocation letter.
This opens massive opportunities for professionals working on government buildings, schools, universities, and military facilities. Many of the largest commercial buildings in the United States are owned by non-tax-paying entities, and Congress specifically expanded 179D to allow designers to claim the deduction in those cases.
Most architects and engineers don’t know this exists.
What this means for you: If you design buildings for government entities, nonprofits, or educational institutions, you’re leaving substantial deductions unclaimed.
Understanding the June 30, 2026 Deadline
The One Big Beautiful Bill Act added a termination provision. Section 179D won’t apply to any property where construction begins after June 30, 2026.
That’s a hard cutoff. No extensions. No phase-out period. If your project starts after that date, the deduction is gone.
The IRS defines “beginning construction” in two ways. The first is the physical work test, where significant on-site work has started. The second is the 5% safe harbor test, where at least 5% of total project costs have been incurred.
Understanding these definitions matters because they determine whether you lock in eligibility or miss the window.
For building owners who’ve been considering energy-efficient upgrades, the clock is ticking. For developers with projects in the pipeline, the deadline creates urgency around timing and documentation.
Action point: If you have commercial construction or renovation projects planned, verify your start date against the IRS definitions to confirm eligibility before June 30, 2026.
How 179D Works With Cost Segregation
David’s approach to tax strategy is additive. If a building qualifies for cost segregation, that’s a baseline move. If it also qualifies for 179D, you claim both.
Cost segregation accelerates depreciation by reclassifying components of a building into shorter recovery periods. 179D provides an immediate deduction for energy-efficient systems. They work together, not against each other.
This is where the partnership with Brian and CSSI becomes relevant. David handles the initial contact and assessment. If 179D or R&D expertise is needed, Brian steps in. The model keeps each person operating in their area of depth while ensuring clients get comprehensive coverage.
The structure is built on specialization, not breadth. It works because the goal isn’t to sell everything to everyone. The goal is to deliver what serves.
Why this matters: Treating 179D and cost segregation as complementary strategies maximizes deductions without creating conflicts or redundancies.
The Deduction Range: $0.50 to $5.81 Per Square Foot
The deduction amount isn’t fixed. It ranges from $0.50 per square foot at the base level to $5.81 at the enhanced tier.
What drives that 10x difference? Prevailing wage requirements and apprenticeship programs. Buildings that meet specific labor standards qualify for the higher deduction. Those that don’t still get the base amount.
David doesn’t dive deep into the hiring criteria during initial conversations, and that’s intentional. The goal is to determine whether 179D applies. Once eligibility is confirmed, the specifics get handled through the study process.
This is the pattern across his entire approach. Start with the question that matters most. Then layer in complexity only when it’s relevant.
Practical takeaway: Don’t let wage and apprenticeship requirements deter you from exploring 179D. Even projects that don’t meet enhanced criteria still qualify for the base deduction.
What You Should Do Next
If you own commercial property or design buildings for tax-exempt entities, the question isn’t whether 179D applies. The question is whether you’ve explored it.
Real numbers back this up. A Fortune 500 company with a 46-million-square-foot portfolio spanning over 350 U.S. facilities realized a $26 million tax deduction through ongoing maintenance and renovations under Section 179D.
That’s not an outlier. That’s what happens when you apply the deduction systematically across a portfolio.
The deadline adds urgency, but the opportunity has always been there. The difference now is awareness. And the willingness to ask your advisor a simple question: “Have we looked at 179D?”
If the answer is no, you’re not alone. You’re also leaving money on the table that doesn’t need to stay there.
Frequently Asked Questions About Section 179D
Who is eligible to claim the 179D deduction?
Commercial building owners who install energy-efficient HVAC, lighting, building envelope, or water heating systems qualify. Residential properties over four stories with more than 40,000 square feet also qualify. For tax-exempt properties, the deduction transfers to the designer, architect, or engineer.
How often do I qualify for the 179D deduction?
Private building owners qualify every three years per building. Tax-exempt properties qualify every four years. This means ongoing renovations and upgrades generate recurring deductions.
Does the deduction work retroactively?
Yes. If you didn’t claim 179D when the building was placed in service, you file Form 3115 to claim it retroactively without amending prior tax returns. This allows you to capture missed deductions from previous years.
What happens after June 30, 2026?
Projects that begin construction after June 30, 2026 won’t qualify for 179D under current law. The IRS defines “beginning construction” through either the physical work test or the 5% safe harbor test. Lock in eligibility before the deadline.
How does 179D work with cost segregation?
179D and cost segregation are complementary strategies. Cost segregation accelerates depreciation by reclassifying building components into shorter recovery periods. 179D provides an immediate deduction for energy-efficient systems. You claim both when applicable.
What’s the difference between the $0.50 and $5.81 deduction rates?
Buildings that meet prevailing wage and apprenticeship requirements qualify for the enhanced $5.81 per square foot deduction. Buildings that don’t meet those labor standards still receive the base $0.50 per square foot deduction.
Why don’t CPAs mention 179D to their clients?
Most CPAs focus on tax preparation and compliance, not proactive tax strategy. Identifying deductions like 179D requires a different skill set and service model. The incentive structure in traditional tax practices rewards efficient filing, not strategic planning.
Where do I start if I think my building qualifies?
Begin with a preliminary analysis. Gather information about your building’s size, construction date, and any energy-efficient systems installed. Contact a tax strategist who specializes in 179D to determine eligibility and coordinate the engineering study required for documentation.
Key Takeaways
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Section 179D has existed since 2006 and became permanent in 2020. The deduction reaches up to $5.81 per square foot for qualifying energy-efficient commercial buildings.
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Most building owners never hear about 179D because tax preparers focus on compliance, not proactive strategy. The gap is systemic, not accidental.
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June 30, 2026 is a hard deadline. Projects that begin construction after that date will no longer qualify. Understanding the IRS definitions of “beginning construction” matters for locking in eligibility.
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Designers receive the deduction on government projects. If the building owner doesn’t pay federal tax, they allocate the deduction to the architect, engineer, or contractor through a simple letter.
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179D stacks with cost segregation. If your building qualifies for both strategies, you claim both. They’re complementary, not competing.
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Retroactive claims work through Form 3115. If you didn’t claim 179D when the building was placed in service, you still have time to go back without amending prior returns.
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The deduction exists. The deadline is real. The question is whether you’re going to explore it before the window closes.
For more information on this and other tax strategies you use to avoid paying more to the IRS than you need to, follow The Tax Strategy Playbook Podcast at https://taxstrategyplaybook.com
For a free preliminary analysis of your building, contact me directly at David.Wiener@cssiservices.com









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