Modification of decree for maintenance or support, property disposition – Termination of maintenance obligation and child support – Grounds. (1) Except as otherwise provided in RCW 26.09.070(7), the provisions of any decree respecting maintenance or support may be modified: (a) Only as to installments accruing subsequent to the petition for modification or motion for adjustment except motions to compel court-ordered adjustments, which shall be effective as of the first date specified in the decree for implementing the adjustment; and, (b) except as otherwise provided in this section, only upon a showing of a substantial change of circumstances. The provisions as to property disposition may not be revoked or modified, unless the court finds the existence of conditions that justify the reopening of a judgment under the laws of this state. (2) Unless otherwise agreed in writing or expressly provided in the decree the obligation to pay future maintenance is terminated upon the death of either party or the remarriage of the party receiving maintenance or registration of a new domestic partnership of the party receiving maintenance. (3) Unless otherwise agreed in writing or expressly provided in the decree, provisions for the support of a child are terminated by emancipation of the child or by the death of the parent obligated to support the child. (4) Unless expressly provided by an order of the superior court or a court of comparable jurisdiction, provisions for the support of a child are terminated upon the marriage or registration of a domestic partnership to each other of parties to a paternity order, or upon the remarriage or registration of a domestic partnership to each other of parties to a decree of dissolution. The remaining provisions of the order, including provisions establishing paternity, remain in effect. (5)(a) A party to an order of child support may petition for a modification based upon a showing of substantially changed circumstances at any time. (b) An obligor’s voluntary unemployment or voluntary underemployment, by itself, is not a substantial change of circumstances. (6) An order of child support may be modified one year or more after it has been entered without a showing of substantially changed circumstances: (a) If the order in practice works a severe economic hardship on either party or the child; (b) If a party requests an adjustment in an order for child support which was based on guidelines which determined the amount of support according to the child’s age, and the child is no longer in the age category on which the current support amount was based; (c) If a child is still in high school, upon a finding that there is a need to extend support beyond the eighteenth birthday to complete high school; or (d) To add an automatic adjustment of support provision consistent with RCW 26.09.100. (7)(a) If twenty-four months have passed from the date of the entry of the order or the last adjustment or modification, whichever is later, the order may be adjusted without a showing of substantially changed circumstances based upon: (i) Changes in the income of the parents; or (ii) Changes in the economic table or standards in chapter 26.19 RCW. (b) Either party may initiate the adjustment by filing a motion and child support worksheets. (c) If the court adjusts or modifies a child support obligation pursuant to this subsection by more than thirty percent and the change would cause significant hardship, the court may implement the change in two equal increments, one at the time of the entry of the order and the second six months from the entry of the order. Twenty-four months must pass following the second change before a motion for another adjustment under this subsection may be filed. (8)(a) The department of social and health services may file an action to modify or adjust an order of child support if public assistance money is being paid to or for the benefit of the child and the child support order is at least twenty-five percent above or below the appropriate child support amount set forth in the standard calculation as defined in RCW 26.19.011 and reasons for the deviation are not set forth in the findings of fact or order. (b) The department of social and health services may file an action to modify or adjust an order of child support in a nonassistance case if: (i) The child support order is at least twenty-five percent above or below the appropriate child support amount set forth in the standard calculation as defined in RCW 26.19.011; (ii) The department has determined the case meets the department’s review criteria; and (iii) A party to the order or another state or jurisdiction has requested a review. (c) The determination of twenty-five percent or more shall be based on the current income of the parties and the department shall not be required to show a substantial change of circumstances if the reasons for the deviations were not set forth in the findings of fact or order. (9) The department of social and health services may file an action to modify or adjust an order of child support under subsections (5) through (7) of this section if: (a) Public assistance money is being paid to or for the benefit of the child; (b) A party to the order in a nonassistance case has requested a review; or (c) Another state or jurisdiction has requested a modification of the order. (10) If testimony other than affidavit is required in any proceeding under this section, a court of this state shall permit a party or witness to be deposed or to testify under penalty of perjury by telephone, audiovisual means, or other electronic means, unless good cause is shown.