Frequently Asked Questions

Can a project completed after June 30, 2026 still qualify for 179D?

Possibly. The deadline focuses on when construction begins, not only when the project is completed. A project completed after June 30, 2026 may still be worth reviewing if construction began on or before the deadline.

What types of projects should be reviewed?

Commercial new construction, building upgrades, lighting projects, HVAC improvements, and building envelope improvements may be worth reviewing if they involve eligible energy-efficient property. The IRS lists interior lighting, HVAC, and building envelope property as eligible building systems under 179D.
What documentation may be needed?

Project owners should gather contracts, permits, construction schedules, invoices, project records, energy modeling, inspection records, and any documentation that helps show when construction began and what energy-efficient systems were installed.

Why does the construction start date matter?

Because the current termination rule says 179D does not apply to property where construction begins after June 30, 2026. Projects already underway before that date may need a closer review before assuming the deduction is unavailable.

Many commercial building owners, developers, designers, and contractors are now asking the same question:

If a project was already underway before June 30, 2026, can it still qualify for the 179D deduction?

The answer may be yes, depending on when construction began, when the energy-efficient property is placed in service, and whether the project meets the other 179D requirements.

Recent IRS guidance says the Section 179D deduction is terminated for property where construction begins after June 30, 2026. That makes the construction start date especially important for projects that were already in progress around the deadline.

What Changed for 179D After June 30, 2026?

Section 179D provides a deduction for certain energy-efficient commercial building property.

The recent change added a deadline tied to when construction begins. Under the current rule, 179D will not apply to property where construction begins after June 30, 2026.

That does not automatically mean every project completed after June 30, 2026 is out.

For projects that were already underway, the more important question may be: when did construction begin?

That detail can make a meaningful difference.

Can Projects Already Underway Still Qualify?

Projects already underway before the deadline may still be worth reviewing.

A commercial building project does not always move neatly from design to construction to completion. Some projects begin before the deadline but are not completed or placed in service until months later.

That is why it is important not to look only at the completion date.

A project completed after June 30, 2026 may still have a potential 179D opportunity if construction began on or before the deadline and the project meets the other requirements.

This is where documentation becomes important. The project team may need to support when construction began, what work was performed, and which building systems were installed.

What Does “Placed in Service” Mean?

“Placed in service” generally means the property is ready and available for its intended use.

For 179D, this still matters because the deduction is tied to qualifying energy-efficient commercial building property placed in service during the tax year. The IRS also says Form 7205 is used to calculate and claim the deduction for qualifying energy-efficient commercial building property placed in service during the tax year.

In simple terms, construction start date and placed-in-service date both matter, but they answer different questions.

The construction start date may help determine whether the project is affected by the June 30, 2026 deadline.

The placed-in-service date helps determine when the deduction may be claimed.

What Building Systems May Be Reviewed?

179D is not for every improvement in a commercial building.

The deduction generally focuses on eligible energy-efficient property installed as part of specific building systems.

That may include:

• Interior lighting
• HVAC
• Building envelope improvements

The Department of Energy also notes that 179D applies to eligible property placed in service as part of new construction or a building upgrade project.

This means projects involving lighting upgrades, HVAC improvements, envelope work, or larger energy-efficient construction should be reviewed carefully.

A new paint job is probably not the 179D conversation. But a larger project involving energy modeling, lighting systems, HVAC, or building envelope improvements may be.

What Documentation Should Project Owners Gather?

For projects near the June 30, 2026 deadline, documentation may be one of the most important parts of the review.

Project owners may want to gather:

• Construction contracts
• Permits
• Notices to proceed
• Project schedules
• Contractor invoices
• Pay applications
• Drawings and specifications
• Energy models
• Inspection records
• Certificates of occupancy
• Commissioning documents
• Records showing when work began

The goal is to support the project timeline and show which energy-efficient systems were installed.

If the project started before the deadline but the records are scattered across emails, contractors, folders, and accounting files, it is better to organize them sooner rather than later.

Why Projects Completed After the Deadline Should Still Be Reviewed

A project completed after June 30, 2026 should not automatically be dismissed.

The deadline is tied to when construction begins, not just when the project is finished. That means owners, designers, and contractors should look at the actual project timeline before assuming the opportunity is gone.

This is especially important for projects that were already in motion before June 30, 2026 but were completed later.

The practical question is simple:

Did construction begin before the deadline, and can the project team support that with documentation?

If the answer may be yes, the project is worth reviewing.

How Specialty Tax Group Helps Review 179D Timing

Specialty Tax Group helps commercial building owners, designers, and project teams evaluate whether 179D may apply.

For projects near the June 30, 2026 deadline, that means reviewing the project timeline, construction start date, placed-in-service date, energy-efficient systems, and available documentation.

STG can help determine whether a project should be reviewed further and what information may be needed to support the deduction.

The goal is not to assume every project qualifies.

The goal is to make sure eligible projects are not missed simply because they were completed after the deadline.

Final Takeaway

The June 30, 2026 deadline does not necessarily eliminate every project completed after that date.

If construction began on or before June 30, 2026, the project may still be worth reviewing.

The key is documentation.

Commercial building owners, designers, and contractors should review when construction began, when the property was placed in service, and whether eligible energy-efficient systems were installed.

If your project was already underway before June 30, 2026, Specialty Tax Group can help evaluate whether 179D may still apply.