What is the §179D deduction worth?

The §179D energy-efficient commercial buildings deduction lets a business deduct the cost of qualifying efficiency improvements — to lighting, HVAC, or the building envelope — up to a per-square-foot maximum that is significantly higher when prevailing wage and apprenticeship requirements are met. It is a deduction (reducing taxable income), not a dollar-for-dollar credit.

What is the §48 investment tax credit?

The §48 investment tax credit is a percentage credit against income tax for investing in energy property such as solar, and certain other qualifying systems placed in service. The base credit is modest, but meeting prevailing wage and apprenticeship requirements raises it substantially, and bonus adders can increase it further. Newer projects may instead fall under the §48E technology-neutral credit.

What is the difference between a deduction and a credit here?

§179D is a deduction — it lowers the income your business is taxed on, so its value depends on your tax bracket. §48 is a credit — it reduces your tax bill dollar for dollar. A $1 credit is generally worth more than a $1 deduction, but the two apply to different investments: efficiency improvements versus clean-energy generation property.

Do prevailing wage and apprenticeship rules apply to small projects?

For §179D and §48, meeting prevailing wage and apprenticeship requirements unlocks the much larger incentive amounts, but there are exceptions — including for smaller projects below certain size thresholds, which can qualify for the higher rate without meeting those labor requirements. Confirm the current thresholds before assuming your project is exempt.

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Business Tax Credits

Business Energy Tax Incentives: §179D and §48 for Small Businesses

Two federal incentives reward businesses that invest in energy efficiency and clean power: the §179D deduction for efficient commercial buildings and the §48 investment credit for solar and other energy property. Here's how each works and which one fits your project.

SMAART Tax Team

February 24, 2026

6 min read

|Reviewed by Lisa Terrell, Enrolled Agent