A Section 179D allocation letter is the written statement in which a specified tax-exempt building owner allocates its deduction for energy efficient property to the person primarily responsible for designing that property. Under the Instructions for Form 7205 (Rev. December 2025), the designer can claim only the amount the owner allocates, and the allocation has to be in writing and meet Notice 2008-40, section 3.04. Owners that can allocate include government entities, Indian tribal governments, Alaska Native corporations and organizations exempt from tax under chapter 1. No deduction is allowed for property whose construction begins after June 30, 2026 (section 179D(i)), so an allocation can relate only to property whose construction began on or before that date.
What the Statute and Form 7205 Require
The statute leaves the details to Treasury. Section 179D(d)(3) directs Treasury to “promulgate regulations or guidance to allow the allocation of the deduction to the person primarily responsible for designing the property in lieu of the owner,” and treats that person as the taxpayer. The retrofit alternative in section 179D(f) applies rules similar to subsection (d)(3).
Three conditions on Form 7205. A designer checks the Designer box only if it is the person primarily responsible for designing the property, it created the technical specifications for installing the property on or in the owner’s building, and “the specified tax-exempt entity building owner provided you a written statement allocating the deduction to you.” A person that merely installs, repairs or maintains the property is not a designer. The designer enters the allocated amount on line 2, column (j), and completes Part IV with information about the owner and “the individual completing the allocation form.”
| Item the claim relies on | Where it is required |
| Owner is a specified tax-exempt entity | Section 179D(d)(3) |
| Recipient created the technical specifications | Form 7205 instructions |
| Allocation in writing | Form 7205 instructions; Notice 2008-40, section 3.04 |
| Owner and designer signatures; owner declaration | Notice 2008-40, section 3.04 |
| Amount allocated | Form 7205, line 2, column (j) |
| Owner and individual completing the allocation | Form 7205, Part IV |
| Certification by a qualified individual | Form 7205 instructions |
Notice 2008-40 holds the content list. Section 3.04 of the notice requires a written allocation that gives the name, address and telephone number of an authorized representative of the owner and of the designer, the address of the building, the cost of the property, the date the property is placed in service and the amount allocated, and that carries both representatives’ signatures and the owner representative’s declaration under penalties of perjury. Under section 3.05, the allocation need not be attached to the return and should be kept with the designer’s records. The notice addressed government-owned buildings, and the IRS’s Section 179D page lists it with requirements for property placed in service before January 1, 2023, so a designer working with another type of owner should confirm how its items apply. Our guide to IRS Form 7205 walks through the rest of the form.
Which Owners Can Allocate After the Inflation Reduction Act
Before 2023, government owners only. The earlier text of the allocation rule, shown in the Code’s amendment notes, covered property owned by “a Federal, State, or local government or a political subdivision thereof.” The Inflation Reduction Act of 2022 rewrote the rule to cover property owned by a “specified tax-exempt entity.”
The specified tax-exempt entity list. As the Form 7205 instructions and the Department of Energy summarize section 179D(d)(3), the term covers:
- the United States, a state or political subdivision, a U.S. possession, or an agency or instrumentality of any of them;
- an Indian tribal government (as defined in section 30D(g)(9)) or an Alaska Native corporation;
- any organization exempt from tax under chapter 1 of the Code, such as an organization described in section 501(c)(3).
The IRS describes the expansion as available beginning January 1, 2023, and the Form 7205 instructions apply the Inflation Reduction Act changes to property placed in service after December 31, 2022. The Form 7205 instructions also say the building owner must reduce the basis of the property by the amount of the deduction allocated.
Timing Against the Placed-in-Service Date and the Designer’s Return
The tax year follows placement in service. Section 179D(a) allows the deduction for property “placed in service during the taxable year,” and Notice 2008-40, section 3.01, allows it to the designer for the taxable year that includes the placed-in-service date. A designer reports the allocated deduction on Form 7205 filed with that year’s return.
The letter comes before the claim. The designer needs the written statement to check the Designer box, and Notice 2008-40, section 3.05, requires the designer to obtain the allocation before claiming the deduction. Section 3.04 asks the allocation to state the placed-in-service date, so whether a letter signed before that date is effective is a question for the designer’s adviser.
A letter that arrives late. If the allocation arrives after the designer has filed the return for that year, the designer generally looks to an amended return (a corrected return for that year) while the period of limitations is open. A partnership under the centralized partnership audit regime (a BBA partnership) generally files an administrative adjustment request (AAR), a partnership-level request to adjust a filed return, under separate rules. Our article on Section 179D after the sunset for designers covers lookback timing.
Earlier allocations on the same building. For property placed in service after December 31, 2022, deductions claimed for the building in the prior 3 tax years, or 4 tax years for an allocated deduction, reduce the maximum deduction before the current-year amount is computed (section 179D(b); Form 7205 instructions). Under prior law, all earlier deductions for the building counted, so in either case the owner’s record of earlier allocations matters to the designer. Under Notice 2008-40, section 3.03, where more than one designer created the technical specifications, the owner either allocates the full deduction to the designer primarily responsible or, at its discretion, divides it among several designers.
Projects Under Way at the June 30, 2026 Construction-Start Limit
Section 179D(i) provides that the section “shall not apply with respect to property the construction of which begins after June 30, 2026,” and the Form 7205 instructions describe the One Big Beautiful Bill Act (OBBBA) as terminating the deduction on those terms. For a project whose construction began on or before that date, the termination does not by its terms prevent an allocation when the property is placed in service in a later year. The limit runs from the construction start, not from the date of the letter or the return.
Two points remain open in the sources we reviewed:
- When construction begins. The statute does not define it, and we did not find IRS guidance on it for Section 179D.
- Retrofit plans and phased work. How the date applies to property installed under a qualified retrofit plan, or to a phased project with several start dates, is not addressed.
Records showing when construction started belong in the designer’s file with the allocation and certification. Our guide on how to claim the 179D deduction lists broader documentation, and our overview of Section 179D for architects and engineers covers eligibility.
To see where your firm’s allocation letters and project dates stand under these rules, you can request a no-cost analysis from CSSI Services; the Section 179D services page describes the study.
Frequently Asked Questions
Who signs a Section 179D allocation letter?
Under Notice 2008-40, section 3.04, authorized representatives of both the building owner and the designer sign the allocation, and the owner’s authorized representative also signs a declaration under penalties of perjury. Form 7205, Part IV, asks for information about the owner and the individual completing the allocation form. The notice was written for government-owned buildings, so confirm with your adviser how it applies to other specified tax-exempt owners.
Can a nonprofit owner allocate the Section 179D deduction?
According to the Form 7205 instructions, yes, for property placed in service after December 31, 2022, if the owner is an organization exempt from tax under chapter 1. Before then, the allocation rule covered only government owners.
Can a designer claim the deduction without an allocation letter?
Generally not. The Form 7205 instructions condition the Designer box on a written statement from the specified tax-exempt owner allocating the deduction, and a designer may claim only the amount allocated.
Can the owner split the deduction among several designers?
Each designer claims only the amount allocated to it. Under Notice 2008-40, section 3.03, where more than one designer created the technical specifications, the owner either allocates the full deduction to the designer primarily responsible or, at its discretion, divides it among several designers. The notice was written for government-owned buildings, so confirm with your adviser how it applies to other owners.
Can a project that started construction before July 1, 2026 still produce an allocation letter?
Generally yes. Section 179D(i) bars the deduction for property whose construction begins after June 30, 2026, so an earlier start can still support an allocation once the property is placed in service. The statute does not define when construction begins, so keep records of the start date.
This article provides general information about federal tax rules and is not tax advice. Speak with your tax adviser about your specific circumstances.
