A midyear move requires separate calculations for Washington residency, income source, and the standard deduction. Under the enacted income tax beginning in 2028, the deduction is adjusted by an income ratio—not simply the fraction of the year you lived here.
The examples below illustrate that distinction. They assume Washington residency actually ends and later income has no Washington source. A change of address or payment date alone does not establish either assumption. For the broader framework, see the relocation guide.
Determine the resident and nonresident portions
Under RCW 82A.04.450, enacted as §406 of ESSB 6346, a part-year resident generally includes all adjusted gross income from the resident portion and Washington-source income from the nonresident portion, subject to the statute’s other modifications.
Pass-through items have a separate rule. The resident component uses the item’s total amount multiplied by resident days divided by days in the entity’s tax year. The nonresident component uses the Washington-source amount multiplied by the corresponding nonresident-day ratio. Do not allocate every item solely by when cash was distributed.
Adjust the deduction by income
RCW 82A.04.363, enacted as §315, adjusts the standard deduction for taxpayers who are not residents for the entire year. Multiply the applicable deduction by Washington base income divided by federal adjusted gross income from all sources, with the fraction capped at one.
For 2028, the starting deduction is $1 million, shared by spouses and state-registered domestic partners regardless of filing status. These simplified examples assume $4 million of federal AGI, the stated Washington base income after applicable modifications, and no deductions other than the adjusted standard deduction or credits.
| Calculation | Example 1 | Example 2 |
|---|---|---|
| Federal AGI | $4,000,000 | $4,000,000 |
| Washington base income | $2,000,000 | $500,000 |
| Deduction ratio | 50% | 12.5% |
| Adjusted deduction | $500,000 | $125,000 |
| Washington taxable income | $1,500,000 | $375,000 |
| Tax at 9.9%, before credits | $148,500 | $37,125 |
Example 1 assumes $2 million belongs in Washington base income and $2 million is non-Washington-source income from the nonresident period.
Example 2 — lumpy income, well-timed. Same move date, same $4 million AGI — but $3.5 million is a post-move income event that is not Washington-source income, such as a short-term gain from intangible property that is not employed in a Washington business. Washington base income is $500,000. Deduction: $1M × ($0.5M / $4M) = $125,000. Taxable income: $375,000. Tax at 9.9%: $37,125. The day count is identical to Example 1; the location and character of the income event changed the result.
The $111,375 difference depends on those facts. For employee compensation, post-move payment does not necessarily mean post-move income: compensation for services performed both inside and outside Washington is generally apportioned based on Washington workdays over total workdays, or another reasonable method approved by DOR. A bonus for Washington services can remain Washington-source compensation even if paid after departure. These are income-tax illustrations, not estimates for a long-term stock sale.
Keeping a Washington home needs separate review
RCW 82A.04.010(8)(c) makes residency a part-year determination: an individual who is a Washington resident for only part of the year is treated as a resident for that portion. But keeping a Washington home after changing domicile does not, by itself, automatically extend Washington residency through the rest of the year. A person no longer domiciled here can still be a statutory resident if the separate abode-and-presence test is met — maintaining a place of abode in Washington and being physically present here for more than 183 days during the taxable year. The date a former domiciliary actually ceases to be a Washington resident therefore depends on the domicile and statutory-residency rules, not simply on whether a Washington residence remains available.
Keep the statutory tests distinct. The abode-and-presence rule above (more than 183 Washington days with a Washington abode) is for someone no longer domiciled here. Separately, a domiciliary exception requires no permanent Washington abode throughout the year, a permanent abode elsewhere throughout the year, and no more than 30 Washington days. Any portion of a calendar day counts. See the 30-day rule guide.
Calculate long-term stock gains separately
For a typical sale of stock or another intangible subject to chapter 82.87, domicile at the time of sale is a central allocation question. The chapter 82.87 allocation rules and any applicable exceptions should be analyzed separately from the part-year income-tax calculation. Identify the sale or exchange rather than assuming the cash-payment date controls. The new income tax separately modifies federal long-term gains and losses and provides a credit for Washington capital gains tax.
Do not apply the table above directly to gross stock-sale proceeds or infer that changing domicile resolves every income-tax question. See the two-tax calculation for the addback, deduction, and credit mechanics.
Build a move-year calculation
The planning point is that the move date, the character and source of each income item, and when the item enters federal AGI all matter. A day-count shortcut does not answer the question. List expected income events, establish the resident periods, determine each item’s character and source, and apply the deduction ratio. Preserve the move, housing, work-location, and transaction records supporting those inputs. Review guidance applicable to the filing year before relying on a proposed treatment.
For help reviewing your timeline and assumptions, book a 20-minute call with Joe Wallin.
Last reviewed: September 14, 2026. General educational information, not legal or tax advice for a particular move.
