Washington § 82.87.120 - Joint filers — Separate filers — Tax liability.

(1) If the federal income tax liabilities of both spouses are determined on a joint federal return for the taxable year, they must file a joint return under this chapter.

(2) Except as otherwise provided in this subsection, if the federal income tax liability of any individual, including either spouse of a marital community, is determined on a separate federal return for the taxable year, they must file separate returns under this chapter. State registered domestic partners may file a joint return under this chapter even if they filed separate federal returns for the taxable year.

(3) The liability for tax due under this chapter of each spouse or state registered domestic partner is joint and several, unless:

(a) The spouse is relieved of liability for federal tax purposes as provided under Title 26 U.S.C. Sec. 6015 of the internal revenue code; or

(b) The department determines that the domestic partner qualifies for relief as provided by rule of the department. Such rule, to the extent possible without being inconsistent with this chapter, must follow Title 26 U.S.C. Sec. 6015.

(4)(a) Unless the context clearly indicates otherwise, individuals who are spouses or state registered domestic partners are not considered separate taxpayers for the purposes of this chapter regardless of whether they file a joint or separate return for the tax imposed under this chapter. The activities and assets of each spouse or state registered domestic partner are combined as if they were one individual for the purposes of determining the applicability of any threshold amounts, caps, deductions, credits, or any other amounts related to the activities or assets of an individual throughout this chapter.

(b)(i) Except as provided in (b)(ii) of this subsection (4), when an individual does not file a joint return for the tax imposed under this chapter, both spouses or state registered domestic partners must allocate between themselves their respective share of the marital community's or domestic partnership's assets and activity. The allocation must be reported to the department on any returns required to be filed pursuant to this chapter in a manner prescribed by the department.

(ii) If both spouses or state registered domestic partners cannot agree on an allocation of assets and activity as authorized under (b)(i) of this subsection (4), each spouse is limited to one-half of the total assets and activities of their marital community or domestic partnership.

Effective date—2025 c 409 ss 3, 4, 8, 10, and 15: See note following RCW 82.87.160.

Automatic expiration date and tax preference performance statement exemption—2021 c 196: See note following RCW 82.87.010.