179D Is Gone. Here's What to Do Instead.

The Short Version

Section 179D sunsets June 30, 2026. After that date, no new projects can use it. But the federal and state incentive landscape for commercial buildings doesn't disappear — it shifts. The ITC safe harbor locks in a 30% solar tax credit through 2030. C-PACE provides off-balance-sheet capital for virtually any energy upgrade. MACRS accelerated depreciation has no sunset. And state-level programs in California, New York, Texas, Massachusetts, and Illinois stack on top of everything.

The total available incentive per project — across federal, state, and utility programs — often runs $100,000 to $500,000+ for a mid-size commercial building. 179D was one piece of that stack. Its expiration doesn't end the opportunity; it just changes the playbook.

The Investment Tax Credit (ITC) under the Inflation Reduction Act allows commercial property owners to claim 30% of the total cost of a qualifying solar installation as a federal tax credit. An optional +10% domestic content bonus applies when equipment is manufactured in the United States. There is also a potential +10% energy community adder for projects in qualifying census tracts.

Safe Harbor Deadline

ITC safe harbor requires that qualifying construction begins no later than December 31, 2026. Once safe harbor is established, the project can be placed in service anytime through December 31, 2030 and still claim the 30% rate. This is a critical planning window: you have until end of 2026 to "start the clock," but nearly four years to complete and deploy the system.

Example Value: 100kW Commercial Solar System

Assuming a 100kW rooftop system at $3.15/W installed cost (2026 market average):

• System cost: $315,000
• 30% ITC: $94,500
• +10% domestic content bonus: $31,500 additional (if qualifying equipment used)
• Total tax credit value: $94,500 – $126,000
• MACRS 5-yr depreciation (bonus year 1): Saves additional $25,000 – $40,000 in taxes depending on marginal rate
• Combined ITC + MACRS value: ~$119,500 – $166,000 on a $315,000 project

Sources: Arnold & Porter OBBBA Analysis (2025); IRS Notice 2018-59; IRS Rev. Proc. 2023-33.

Commercial Property Assessed Clean Energy (C-PACE) financing is one of the most underused tools for building owners. Unlike a traditional loan, C-PACE repayment is structured as a property tax assessment — which means it stays with the building, not the borrower, and does not appear on the company's balance sheet as debt.

How It Works

1. 1
   Apply through your state's C-PACE administrator

   Most states have a dedicated C-PACE program. Applications typically take 4–8 weeks for smaller projects. Over $10 billion has been deployed nationally via C-PACE since 2008. (Source: PACENation.org)

2. 2
   C-PACE covers 100% of eligible project costs

   Eligible measures include solar, HVAC, LED lighting, EV charging, building envelope, and water efficiency. Some programs also cover seismic and resiliency improvements.

3. 3
   Repayment via property tax bill (10–25 year term)

   Typical interest rates: 6–9%. Because energy savings begin immediately, many C-PACE projects produce net-positive cash flow from month one — you save more in energy costs than you pay in the assessment.

4. 4
   ITC and other credits still apply on top of C-PACE

   The 30% ITC is calculated on the full system cost, regardless of how it's financed. C-PACE financing does not reduce your tax credit eligibility. This is the core stacking strategy: use C-PACE for capital access and ITC for year-one tax savings.

Every state below has active commercial incentive programs that can be stacked with the federal ITC and C-PACE financing. These programs are independent of 179D and continue after June 30, 2026.

Program values are representative ranges for commercial projects as of Q1 2026. Verify current incentive levels directly with program administrators before project planning. Not all programs available in all utility territories.

Modified Accelerated Cost Recovery System (MACRS) allows commercial property owners to depreciate solar energy equipment, EV charging systems, and battery storage over 5 years rather than the standard 39-year depreciation schedule for commercial real property. This dramatically accelerates tax deductions.

Unlike the ITC, MACRS has no expiration date — it applies to any qualifying property placed in service, regardless of when. When combined with the ITC, the total tax benefit in year 1 often represents 55–65% of the project cost returned in tax savings and credits.

MACRS + ITC Combined Example

• $300,000 solar installation
• ITC (30%): −$90,000 from federal tax
• MACRS depreciable basis: $255,000 (must reduce basis by 50% of ITC)
• Year 1 bonus depreciation (if available): up to $255,000 × 35% tax rate = $89,250 additional deduction
• Total year-1 tax benefit: ~$179,250 on a $300,000 project (60%)

For building owners who want the fastest cash payback without waiting for safe harbor timelines, LED lighting retrofits and building envelope improvements (insulation, windows, air sealing) consistently offer the best risk-adjusted returns. The 179D deduction was never the primary economic driver for these measures — utility rebates and operational savings were.

Payback Comparison by Measure

Utility Rebates — LED and Envelope

Most major utilities have active commercial rebate programs for LED retrofits and envelope upgrades that don't require 179D and have no scheduled sunset. Typical rebates:

• LED retrofit: $0.05–$0.25 per kWh saved annually, or $20–$80 per fixture replaced
• HVAC controls / VFDs: $50–$200 per unit or per horsepower reduced
• Building envelope: $0.10–$0.50 per square foot of insulation installed

Use EnergyStackHub's free energy audit to pull applicable rebates for your utility territory automatically.

Frequently Asked Questions