Allocation and apportionment—Part-year income.

(1) Except as provided in subsection (2) of this section, the adjusted gross income of a part-year resident is the sum of the following:(a) For the portion of the year in which the taxpayer was a resident of Washington, the taxpayer's entire adjusted gross income; and(b) For the portion of the year in which the taxpayer was a nonresident, the taxpayer's adjusted gross income derived from sources within this state, as provided in RCW 82A.04.430 through 82A.04.440 and 82A.04.460.(2) The adjusted gross income of a part-year resident with federal adjusted gross income that includes an item of income, gain, loss, deduction, or credit from a pass-through entity must include the sum of the following:(a) The total amount of the item that is taken into account in federal adjusted gross income, multiplied by the ratio of the number of days the taxpayer was a resident of Washington during the tax year of the entity over the total number of days in the tax year of the entity; and(b) The total amount of the item that is taken into account in federal adjusted gross income and that is derived from or connected with sources within this state, as determined under RCW 82A.04.430 through 82A.04.440 and 82A.04.460, multiplied by the ratio of the number of days the taxpayer was a nonresident of Washington during the tax year of the entity over the total number of days in the tax year of the entity.[ 2026 c 238 s 406.]Notes:Findings—Intent—Effect of invalidation of 2026 c 238 s 201—Automatic expiration date and tax preference performance statement exemption—Necessity of act—Intent—Implementation by department of revenue—2026 c 238: See notes following RCW 82A.04.030.