The controlling distinction
June 30, 2026 Does Not Necessarily Mean “Game Over”
One date is creating significant confusion around Section 179D: June 30, 2026.
Under current law, Section 179D generally does not apply to property whose construction begins after that date. That distinction matters.
The rule does not simply say that every building must be completed—or every deduction claimed—by June 30, 2026. Instead, the termination provision focuses on when construction begins.
A qualifying project whose construction began by the statutory cutoff may potentially remain within the Section 179D pipeline even when completion occurs a year, two years, or potentially longer afterward. All other Section 179D requirements must still be satisfied.
The date to remember
June 30, 2026
Construction begins by cutoff ≠ Building completed by cutoff
Construction begins by cutoff ≠ Deduction claimed by cutoff
Timing framework
One Project. Three Different Dates.
One of the easiest ways to understand the remaining opportunity is to stop treating every project date as the same event.
Construction start
Does the project remain within the 179D pipeline?
Current law provides that Section 179D does not apply to property whose construction begins after June 30, 2026. For projects relying on the cutoff, contemporaneous contracts, notices to proceed, invoices, schedules, work records, and pay applications may become important.
Placed in service
When does the opportunity become relevant for the tax return?
Section 179D is claimed with respect to qualifying energy-efficient property placed in service during the applicable tax year. Construction could begin in 2026 while the property is placed in service in 2027, 2028, or later.
Tax return
When is the deduction actually claimed?
The deduction is reported for the applicable taxable year using Form 7205. Filing timing depends on the claimant’s taxable year, return due date, extensions, and specific circumstances.
Simplified calendar-year example
May 2026
Construction begins
September 2028
Property placed in service
2028 Tax Year
Applicable deduction year
2029
Return generally filed
The opportunity can extend years beyond the construction-start cutoff.
Provided the project satisfies all applicable Section 179D requirements.
Portfolio strategy
Think Pipeline — Not Deadline
For firms managing multi-year work, a more useful question is: Which projects were already underway by the cutoff, and when will they be placed in service?
Dates shown are illustrative. Each project's construction-start facts and other Section 179D requirements must be independently evaluated.
Designer opportunity
For Designers, the Pipeline Can Be Especially Valuable
Section 179D is not limited to taxable building owners. For qualifying property installed in buildings owned by specified tax-exempt entities, an eligible designer may receive an allocation from the building owner.
An eligible designer may include the person primarily responsible for creating the technical specifications for qualifying energy-efficient property. Depending on the project, this can potentially include architects, engineers, design-build contractors, energy-service providers, and other qualifying technical designers.
A person that merely installs, repairs, or maintains the property does not become an eligible designer solely from performing that work.
Organize the evidence
The Real Work Now Is Identifying the Pipeline
A strong 179D inventory connects the construction timeline, ownership, design responsibility, technical analysis, allocation, and filing year. Open each file tab to see what it should help establish.
Construction Start Evidence
Records supporting when construction began, including contracts, notices, schedules, invoices, work records, and pay applications.
Building Owner
Confirmation that the property owner is an entity permitted to make a designer allocation.
Design Responsibility
Records connecting the firm to the technical specifications for qualifying systems.
Energy Systems
HVAC and hot water, interior lighting, and building-envelope scope.
Construction Cost Information
Pay applications, invoices, schedules of values, and records that help identify qualifying property costs.
Placed-in-Service Date
Evidence showing when the qualifying property was ready and available for its intended use.
Allocation
The appropriate written allocation executed by the eligible building owner.
Energy Analysis
Evaluation of building performance against the applicable reference standard.
Certification / Verification
Applicable certification and field-verification support.
Prevailing Wage & Apprenticeship
Analysis of whether PWA requirements or exceptions affect the available rate.
Tax Filing
Identification of the taxable year and filing approach for the deduction.
One Project → One Organized 179D File
Illustrative case study — not a guaranteed tax result
A 2026 Project Could Produce a 2028 Deduction
- Project
- Public school building
- Designer
- Mechanical engineering firm
- Construction begins
- May 15, 2026
- Construction period
- 2026–2028
- Placed in service
- August 2028
- Owner
- Specified tax-exempt entity
- Allocation
- Obtained
- Analysis / certification
- Qualifying results assumed; completed
May 2026Construction starts
June 30, 2026Statutory cutoff
2027Construction continues
August 2028Property placed in service
2028 tax yearPotential 179D deduction
2029Return generally filed
The project crossed the 2026 cutoff—but its potential 179D deduction did not necessarily disappear.
The termination provision focuses on property whose construction begins after June 30, 2026. A project beginning by the cutoff may potentially remain eligible when placed in service later, assuming every other applicable requirement is satisfied.
Owner coordination
Don't Forget the Allocation
For designers working on qualifying buildings owned by specified tax-exempt entities, technical qualification is only part of the process. The eligible owner must allocate the deduction through the required written documentation.
179D Allocation Letter
Owner allocates $_____ of the available deduction
Without an executed allocation, a designer cannot claim an allocated deduction.
Waiting years to contact the owner can make records, signatures, project contacts, and supporting documentation harder to obtain. Firms should consider identifying potential allocation opportunities before projects disappear into archived files.
Technical substantiation
Energy Modeling and Certification Still Matter
Being inside the construction-start window does not automatically create a deduction. The project must still satisfy the applicable technical, ownership, allocation, certification, tax, and other requirements.
Proposed building
Actual HVAC, lighting, and envelope design
Reference building
Applicable ASHRAE 90.1 standard
Certified energy savings
Applicable $ / SF rate
The required certification information is reported through Form 7205, and applicable verification and certification requirements must be met. Where prevailing-wage and registered-apprenticeship requirements apply, satisfying them can materially increase the available deduction; they do not apply identically to every project.
A changed market
The Sunset Changes Prospecting — It Doesn't Eliminate the Pipeline
Before June 30, 2026
- New projects
- Existing projects
- Projects under construction
- Recently completed projects
- Prior-year projects
After June 30, 2026
- Projects under construction by the cutoff
- Projects placed in service after the cutoff
- Recently completed projects
- Prior-year opportunities within applicable filing periods
Your future 179D pipeline may already exist in your project history.
Filing history matters
What About Projects From Prior Years?
Some firms may have qualifying property placed in service in earlier years for which a Section 179D deduction was never claimed. Whether an amended-return opportunity remains available depends on the specific taxpayer and tax year.
Federal refund claims are generally subject to time limits based on the return filing date and the date tax was paid. Extensions, filing dates, payments, and special circumstances can change the analysis. No year should be labeled automatically “open” or “closed” without reviewing the taxpayer's actual filing history.
Check filing history
Check filing history
Check filing history
Check filing history
Current / pipeline
The right question isn't “How old is the project?” It is: “Is the applicable tax year still open based on the taxpayer's actual filing circumstances?”
Preserve the record
Build the Inventory Before the Records Disappear
A project starting in 2026 and completing in 2028 may require a firm to look back several years for evidence. The longer the wait, the greater the chance documents become difficult to locate or contacts change.
Contract
Construction records
Drawings
Pay apps
Allocation
Energy model
Certification
Complete record = Audit-ready 179D project file
“179D ended.”
The door closed on certain new construction starts.
But qualifying projects already inside the pipeline may continue moving toward a future deduction.
Portfolio review
Your 179D Pipeline May Already Be on Your Project List
If your firm designed projects for government entities, schools, universities, hospitals, nonprofits, public agencies, or other qualifying tax-exempt owners, the next opportunity may not come from a new project. It may already be under construction—or completed.
- When construction began
- When property was placed in service
- Who owned the building
- What systems your firm designed
- Whether you qualify as a designer
- Whether an allocation is available
- Whether energy requirements are met
- Whether PWA rules or exceptions affect the rate
- Whether the relevant tax year remains available