Federal Solar Investment Tax Credit (ITC) Applicability for Washington Residents
The federal Solar Investment Tax Credit (ITC) is one of the most consequential financial mechanisms available to residential and commercial solar adopters in Washington State. Governed by Internal Revenue Code § 25D for residential installations and § 48 for commercial and business-owned systems, the ITC reduces federal income tax liability dollar-for-dollar based on a percentage of qualifying solar system costs. This page covers the credit's structure, eligibility rules, applicable scenarios for Washington residents, and the boundaries where the ITC does not apply.
Definition and scope
The Solar Investment Tax Credit is a nonrefundable federal income tax credit administered by the Internal Revenue Service (IRS). Under the Inflation Reduction Act of 2022 (Pub. L. 117-169), the residential credit rate was set at 30 percent of the total installed system cost for systems placed in service between 2022 and 2032 (IRS Form 5695 Instructions). The commercial credit under § 48 carries the same 30 percent base rate for most qualifying systems, with potential bonus adders for domestic content, energy communities, and low-income project categories.
Scope of this page: This page addresses the ITC exclusively as it applies to Washington State residents and businesses filing U.S. federal taxes. Washington-specific state incentives — including the sales tax exemption on solar equipment under RCW 82.08.962 — are addressed separately at Washington Solar Incentives and Tax Credits. The ITC is federal law; Washington's Department of Revenue and the Washington Utilities and Transportation Commission (UTC) do not administer or modify it. Local utility interconnection requirements and net metering rules, which interact with solar economics but are distinct from the ITC, are covered at Washington Utility Interconnection Requirements.
The ITC does not apply to:
- Systems financed through third-party ownership structures where the taxpayer does not own the equipment (e.g., leases or power purchase agreements where the installer retains ownership)
- Systems installed on property not used as a residence or qualifying business asset in the tax year the credit is claimed
- Costs attributable to roof repairs or structural work not directly part of the solar installation
How it works
The residential ITC (§ 25D) is claimed on IRS Form 5695 and applied against the taxpayer's federal income tax liability for the year the solar system is placed in service — meaning it is installed, inspected, and operational. The commercial credit (§ 48) is claimed on IRS Form 3468.
Qualified costs that count toward the 30 percent calculation include:
- Solar photovoltaic panels and racking hardware
- Inverters (string, microinverter, or hybrid types)
- Electrical wiring and balance-of-system components directly associated with the solar array
- Battery storage systems that are charged exclusively by solar energy (for residential § 25D claims); standalone storage systems charged from the grid do not qualify under § 25D
- Labor costs for on-site preparation, assembly, and original installation
- Permitting and inspection fees required to place the system in service
Because the ITC is nonrefundable, it can reduce a taxpayer's liability to zero but does not generate a refund for any excess. However, unused credit can be carried forward to subsequent tax years (IRS Publication 946 and the § 25D carryforward provisions). Washington residents whose tax liability is low in the installation year should account for multi-year carryforward planning.
For a foundational understanding of how photovoltaic systems generate the electricity that makes the ITC relevant, see How Washington Solar Energy Systems Work.
Common scenarios
Scenario A — Residential homeowner, system purchase: A Washington homeowner purchases and finances a 9 kW rooftop PV system with a total installed cost of $27,000. At 30 percent, the ITC yields a $8,100 federal tax credit claimed on Form 5695 in the installation year. If the homeowner's federal liability that year is $6,000, the remaining $2,100 carries forward.
Scenario B — Residential homeowner, solar lease: The same homeowner signs a 20-year lease with a solar company that retains equipment ownership. Because § 25D requires the taxpayer to own the system, the homeowner claims no ITC. The installing company, as the system owner, may claim the commercial ITC under § 48.
Scenario C — Battery storage added to existing system: A Washington resident installs a 13.5 kWh battery storage unit alongside an existing rooftop array. If the battery is charged solely from the solar system, its full installed cost qualifies for the 30 percent residential credit under the Inflation Reduction Act's expanded storage provisions.
Scenario D — Small business, commercial property: A Washington agricultural operation installs a 50 kW ground-mounted system on farmland. The system qualifies under § 48; if it meets domestic content requirements (as defined by IRS Notice 2023-29), a 10 percentage point bonus adder may apply, raising the effective credit to 40 percent. Agricultural solar is addressed in more depth at Washington Solar Energy for Agricultural Operations.
The broader regulatory landscape governing solar installations in Washington — including UTC oversight, building codes, and interconnection standards — is documented at Regulatory Context for Washington Solar Energy Systems. For a complete orientation to available incentives, including how the ITC interacts with Washington-level programs, see the Washington Solar Authority home page.
Decision boundaries
The following distinctions determine whether a Washington solar adopter qualifies for the ITC, at what rate, and under which code section:
| Factor | § 25D (Residential) | § 48 (Commercial/Business) |
|---|---|---|
| System owner | Individual taxpayer | Business entity or third-party owner |
| Claimed on | IRS Form 5695 | IRS Form 3468 |
| Credit rate (2022–2032) | 30% base | 30% base + potential adders |
| Battery storage | Qualifies if solar-charged | Qualifies with broader criteria |
| Carryforward | Yes, unused credit carries forward | Yes, subject to passive activity rules |
| Transferability | Not transferable | Transferable under IRA § 6418 provisions |
Credit phase-down schedule under current law (IRS guidance per Inflation Reduction Act):
1. 2022–2032: 30 percent
2. 2033: 26 percent
3. 2034: 22 percent
4. 2035 and beyond: Credit expires unless Congress acts to extend it
Washington residents evaluating system sizing should cross-reference the Washington Solar System Sizing Guide, as total installed cost — and therefore the ITC dollar value — scales directly with system capacity. Those considering battery integration as part of their installation decision can review Washington Solar Battery Storage Options.
The ITC does not interact with Washington's net metering credit structure, which is a utility billing mechanism rather than a tax instrument. Net metering is addressed at Washington Net Metering Explained.
Permitting and inspection completion is a prerequisite for "placed in service" status. A system that passes Washington State building inspection and utility interconnection approval in a given calendar year establishes that year as the ITC claim year. Permitting concepts are detailed at Permitting and Inspection Concepts for Washington Solar Energy Systems.
References
- Internal Revenue Code § 25D — Residential Clean Energy Credit (Cornell LII)
- Internal Revenue Code § 48 — Energy Credit (Cornell LII)
- Inflation Reduction Act of 2022, Pub. L. 117-169 (Congress.gov)
- IRS Form 5695 — Residential Energy Credits (IRS.gov)
- IRS Form 5695 Instructions (IRS.gov)
- IRS Form 3468 — Investment Credit (IRS.gov)
- IRS Notice 2023-29 — Energy Community Bonus Credit (IRS.gov)
- [IRS Credits and Deductions — Residential Clean Energy Credit (IRS.gov)](https://