Washington Bonus Depreciation: No Income Tax Today, Here's the Catch.
Washington has no individual income tax for tax year 2026, so there is no state return to add back or deduct federal §168(k) bonus depreciation. But the Business & Occupation (B&O) tax is levied on gross receipts and allows no expense deductions at all, so a cost segregation study cannot reduce a B&O bill. And a new 9.9% tax on adjusted gross income above $1,000,000 begins January 1, 2028.
Reviewed by Cost Seg Smart Editorial Team · Last verified against WA DOR — Income tax, WA DOR — Business & Occupation tax
The 30-second answer: Washington has no individual income tax for tax year 2026, so there is no Washington return on which to add back or deduct federal bonus depreciation. An individual investor claims the full federal Year-1 §168(k) bonus with no state-level reduction today.
But two things keep this from being simple upside. First, Washington's Business & Occupation (B&O) tax is a gross-receipts tax, and Washington DOR says a business "cannot deduct expenses such as labor, materials, taxes, or other costs of doing business" — so depreciation, of any kind, does not lower a B&O bill. Second, Senate Bill 6346 imposes a 9.9% tax on AGI above $1,000,000 for individuals and joint filers, beginning January 1, 2028 — a real state income tax that a study placed in service today will still be depreciating under.
On a representative Washington single-family rental (the single-family rental band we publish, 9–32% of depreciable basis reclassified, 16% representative), the reclassified components alone generate an estimated $18K–$165K of federal Year-1 depreciation. At the 37% federal top bracket, that is roughly $6,660–$61,570 of federal Year-1 tax savings — with $0 change to a Washington B&O bill either way.
Federal vs Washington, Side by Side
For an individual investor's cost-segregation-reclassified components:
| Tax provision | Federal (IRC) | Washington |
|---|---|---|
| Bonus depreciation under §168(k) | 100% may apply to qualified property acquired and placed in service after January 19, 2025, subject to §168(k) eligibility, related-party/prior-use, binding-contract, and election rules | No state return to add it back to. No individual income tax for tax year 2026 |
| Individual income tax on rental income | Ordinary rates, up to 37% | None for tax year 2026. Effective 2028-01-01, SB 6346 imposes 9.9% on AGI above $1,000,000 (individuals and joint filers) |
| Effect of depreciation on B&O tax | Not applicable | None. B&O is computed on gross receipts; WA DOR: businesses "cannot deduct expenses such as labor, materials, taxes, or other costs of doing business" |
| Federal usability of the deduction | Subject to passive activity, at-risk, basis, and business-interest limits | Same federal limits govern the federal deduction; Washington adds no state-level reduction today |
| MACRS asset class lives | 5 / 7 / 15 / 27.5 / 39 yr per Rev. Proc. 87-56 | No Washington income-tax return uses them today; the federal schedule stands alone |
| Depreciation form the individual files with the state | Form 4562 → Schedule E (rental) or Schedule C (active business) | None today. No individual income tax return to file for tax year 2026 |
Sources: Washington DOR — Income tax, Washington DOR — Business & Occupation tax, IRC §168(k). Federal bonus figures reflect current law; eligibility depends on acquisition and placed-in-service dates and elections.
Why a Washington cost segregation study doesn't touch your B&O bill
This is the point a Washington property owner most often gets wrong, because in nearly every other state, accelerating depreciation lowers a tax bill somewhere at the state level too. In Washington, the Business & Occupation (B&O) tax is computed on gross receipts — revenue before any expense is subtracted. Washington's Department of Revenue is explicit about this: a business "cannot deduct expenses such as labor, materials, taxes, or other costs of doing business" when computing B&O liability.
Depreciation is an expense deduction. That means every form of it is equally irrelevant to a B&O bill: 39-year straight-line depreciation, 100% Year-1 bonus depreciation from a cost segregation study, and everything between them all reduce a B&O bill by exactly the same amount — zero. The study itself does not change; it produces the same engineering-based reclassification, using nationally-recognized construction cost data, MACRS classification per Rev. Proc. 87-56, and IRS Pub 5653 ATG-aligned documentation, whether the property sits in Washington or anywhere else. What changes is that in Washington, none of that reclassification reaches a state tax bill of any kind, because Washington's only broad-based state business tax is not computed from net income in the first place.
None of this reduces the federal benefit. The full federal §168(k) Year-1 bonus is claimed on the federal return exactly as it would be anywhere else. The honest statement is narrower: a Washington cost segregation study delivers its value at the federal level only, and it will not move your B&O number, because nothing can.
The 2028 Washington high-earner tax and your depreciation schedule
Senate Bill 6346, passed in the 2026 session, imposes a 9.9% tax on adjusted gross income above $1,000,000 for individuals and married couples filing jointly. It takes effect January 1, 2028 — it is not part of tax year 2026, and nothing on this page should be read as though it were.
The reason it matters for a cost segregation buyer specifically: MACRS recovery periods run 5, 7, 15, 27.5, or 39 years. A property placed in service today, even with 100% Year-1 bonus on the accelerated components, still carries regular depreciation on the remaining 27.5-year or 39-year basis for decades. A property owner whose AGI is near or could cross $1,000,000 in 2028 or later has a real Washington income tax return to plan for, on income that includes rental income from the same property this study covers. "Washington has no income tax" is an accurate statement about tax year 2026. It is not a statement about the life of the asset you are depreciating, and it should be raised with your CPA as part of any multi-year plan, not assumed to hold indefinitely.
This page will be updated if the record in the 50-state conformity table changes before 2028.
Illustrative numbers: a Washington single-family rental
Using the single-family residential (SFR) band we publish — 9–32% of depreciable basis reclassified into 5/7/15-year property, 16% representative — on a property priced between $250,000 and $650,000, with a 20% residential land allocation, and 100% federal bonus depreciation for eligible components under current law:
| Line item | Federal | Washington |
|---|---|---|
| Purchase price band | $250,000–$650,000 | Same property |
| Depreciable basis (20% land allocation) | $200,000–$520,000 | No Washington depreciation return |
| Reclassified to 5/7/15-yr (9–32% of basis) | $18K–$165K | Not applicable |
| Marginal tax rate | Up to 37% | 0% individual income tax for tax year 2026 |
| Illustrative Year-1 federal tax savings on reclassified components | ~$6,660–$61,570 (37% × $18K–$165K) | $0 change to B&O liability, either way |
Figures are illustrative and use the site's published SFR reclassification band; your result depends on your basis, land allocation, bracket, component mix, and eligibility. Whether the full federal deduction is usable in the current year still depends on your passive-loss, at-risk, basis, and business-interest situation. If the property is held in an entity subject to B&O tax, none of the figures above change that entity's B&O liability, for the reasons above.
See a sample cost segregation report
Look at exactly what your Washington study delivers: the component-by-component 5/7/15-year schedule, the Form 4562-ready numbers, and the documentation your CPA files. Real reports are our best answer to "is this legit?"
Forms your CPA files for a Washington property
For an individual Washington investor, the depreciation workflow is federal-only for tax year 2026, because there is no Washington individual income tax return:
- Federal Form 4562: depreciation and amortization, including the §168(k) bonus deduction on eligible reclassified components. Flows to Schedule E (rental) or Schedule C (active business).
- Schedule E (or Schedule C): the accelerated federal deduction reduces federal taxable income in Year 1, subject to the federal passive-loss, at-risk, basis, and business-interest limits. There is no Washington equivalent for tax year 2026.
- Form 3115 §481(a) section: included only if this is a federal lookback method change on a property placed in service in a prior year (see below).
- B&O tax reporting (if the property is held in a business entity): computed on gross receipts under Washington's B&O rules, independent of the depreciation reported above. Confirm entity-level B&O filing obligations with your advisor; the study does not change what is owed.
The reclassified schedule is the same engineered output regardless of state. In Washington, it is used exactly once — on the federal return.
Form 3115 lookback on a Washington property
If the property was placed in service in a prior tax year and depreciation was reported using a non-segregated method, a federal Form 3115 (Application for Change in Accounting Method) may allow a current-year §481(a) catch-up adjustment for the accelerated depreciation you missed, generally without amending prior returns. This is often the single biggest acceleration mechanism in cost segregation. Any catch-up dollars are illustrative and depend on placed-in-service date, prior depreciation claimed, bonus eligibility, land allocation, and component mix.
In Washington, the lookback is a federal-only calculation for tax year 2026: there is no parallel state §481(a) equivalent to compute and no state schedule to restate, and the catch-up does not affect a B&O bill for the same gross-receipts reason a current-year study does not.
See our full Form 3115 cost segregation guide for federal mechanics, partnership and LLC pass-through treatment, and timing rules.
Should you still do cost segregation in Washington?
Usually yes, for the federal reasons alone — but go in with clear eyes about what a Washington property does and does not gain at the state level:
- The full federal Year-1 bonus is intact, with no state add-back. Washington has no individual income tax for tax year 2026, so there is nothing to reduce the federal deduction at the state level. How much you use in the current year still depends on your passive-loss, at-risk, basis, and business-interest situation.
- It will not lower your B&O bill. The B&O tax is computed on gross receipts and allows no expense deductions, so no amount of accelerated depreciation changes it. If B&O relief is the goal, cost segregation is not the tool.
- Plan for 2028 now, not later. If your AGI could reach $1,000,000, discuss SB 6346's 9.9% tax and your depreciation schedule's multi-year run with your CPA before it takes effect, not after.
The nuance to flag with your CPA is exactly this split: the federal benefit is real and unaffected by anything at the Washington level, the B&O tax is real and unaffected by anything cost segregation does, and a new Washington income tax is coming for high earners in 2028. All three are true at once.
Frequently asked
Does Washington allow bonus depreciation?
The question doesn't quite apply the way it does in most states. Washington has no individual income tax for tax year 2026, so there is no Washington personal income tax return on which federal §168(k) bonus depreciation could be added back, disallowed, or separately allowed. An individual investor claims the full federal Year-1 bonus on the federal return (100% may apply to qualified property acquired and placed in service after January 19, 2025, subject to §168(k) eligibility, related-party/prior-use, binding-contract, and election rules), and there is simply no parallel Washington income-tax calculation to reconcile it against.
Does Washington tax my rental income?
Not through an individual income tax, for tax year 2026. Washington has no individual income tax today. That is a current-law statement, not a permanent one: Senate Bill 6346 (2026 session) imposes a 9.9% tax on adjusted gross income above $1,000,000 for individuals and married couples filing jointly, beginning January 1, 2028. A property placed in service now, whose depreciation schedule (accelerated 5/7/15-year components plus the 27.5- or 39-year remainder) is still running in 2028, is exactly the kind of asset a taxpayer near that AGI threshold should plan around with their CPA.
Does a cost segregation study reduce my Washington B&O tax bill?
No, and this is the point most Washington property owners miss. The Business & Occupation (B&O) tax is levied on gross receipts, not net income. Washington's Department of Revenue states plainly that a business "cannot deduct expenses such as labor, materials, taxes, or other costs of doing business" when computing B&O liability. Depreciation is an expense deduction, so this applies to depreciation of every kind — accelerated bonus depreciation from a cost segregation study, ordinary straight-line MACRS, all of it. None of it lowers a B&O bill. A cost segregation study still delivers its full value at the federal level; it does nothing for Washington's gross-receipts tax, because nothing can.
What is Washington's Senate Bill 6346, and does it affect a property I place in service now?
SB 6346, passed in the 2026 session, imposes a 9.9% tax on adjusted gross income above $1,000,000 for individuals and married couples filing jointly, effective January 1, 2028. It is not yet in effect for tax year 2026. The reason it belongs on this page: a MACRS depreciation schedule from a cost segregation study routinely runs 5, 7, 15, 27.5, or 39 years, so a property placed in service today will still be generating depreciation deductions well past 2028. An owner whose AGI is near or above the $1,000,000 threshold should discuss the interaction between their depreciation schedule and this new Washington tax with their CPA before assuming Washington will remain a no-income-tax state indefinitely.
Is cost segregation still worth it in Washington?
For the federal deduction, yes, and Washington adds no state-level reduction to it today. The full federal §168(k) Year-1 bonus is claimed on the federal return, with no Washington add-back, because there is no Washington individual income tax return for tax year 2026. The honest caveats: the study will not reduce a Washington B&O tax bill, because B&O taxes gross receipts and allows no expense deductions of any kind, and an owner whose income may cross $1,000,000 AGI should plan for SB 6346's 9.9% tax beginning in 2028. Whether the current-year federal deduction is fully usable also still depends on federal passive-activity, at-risk, basis, and business-interest limits.
Can I use Form 3115 on a Washington property I bought years ago?
Often, yes, at the federal level. If the property was placed in service in a prior tax year and depreciation was reported using a non-segregated method, a federal Form 3115 (Application for Change in Accounting Method) may allow a current-year §481(a) catch-up for the accelerated depreciation you missed, generally without amending prior returns. Because Washington has no individual income tax for tax year 2026, there is no parallel state adjustment to reconcile; the catch-up is a federal-only calculation. It also does not affect B&O liability, for the same gross-receipts reason a current-year study does not.
What does a Washington cost segregation study rely on for its numbers?
The study reclassifies building components into IRS-recognized MACRS class lives (5, 7, and 15-year) per Rev. Proc. 87-56, using an engineering-based methodology that follows the IRS Cost Segregation Audit Techniques Guide (Publication 5653). The reclassified components may then qualify for federal §168(k) bonus depreciation on the federal return (100% for qualified property acquired and placed in service after January 19, 2025, subject to eligibility and election rules). None of that changes because the property sits in Washington; what changes is that there is no Washington income-tax return to file it against, and no reduction to a B&O bill regardless. The engine ships our own calibrated, nationally-recognized construction cost data.
Related guides
- Bonus depreciation by state: overview
- All 50 states: conformity reference table
- Indiana bonus depreciation (decoupled, first-year add-back)
- Texas bonus depreciation (no state income tax)
- Virginia bonus depreciation (decoupled)
- Form 3115 cost segregation lookback: §481(a) mechanics
- What is cost segregation: the full primer
- Sample cost segregation reports