Seattle Attorneys Blog
Changing a parenting plan in Washington is never easy. The law deliberately makes modifications difficult to protect children from the instability of constant schedule changes. But when a parent’s work schedule changes and they want a modest adjustment to their residential time, the law also provides a pathway: the minor modification under RCW 26.09.260(5). In In re Marriage of McCormick, No. 41124-9-III (Wash. Ct. App. April 9, 2026), the Washington Court of Appeals reversed a trial court’s denial of a father’s petition for a minor modification because the court failed to properly calculate whether the requested change fell within the statute’s 24-day limit. If you are seeking to modify a parenting plan in Washington, this decision illustrates both the process and the pitfalls.
Whether you need to modify an existing parenting plan or respond to a modification petition, the family law team at Blair & Kim can help. Contact us for a confidential case evaluation.
What Is a Minor Modification Under Washington Law?
Washington law distinguishes between major and minor modifications to parenting plans. A major modification—changing the primary residential parent, for example—requires the petitioner to show that the child’s present environment is detrimental or that other specific statutory criteria are met under RCW 26.09.260(1). That is a high bar by design.
A minor modification is different. Under RCW 26.09.260(5), a parent can seek a change to the residential schedule without meeting the higher standard—but only if two conditions are satisfied. First, the parent must demonstrate a substantial change in circumstances. Second, the proposed modification must not exceed 24 full days in a calendar year. If both conditions are met, the court will hold a hearing on the petition. If either condition is not met, the petition is denied at the adequate cause stage before a hearing ever takes place.
What Happened in McCormick?
The father in this case was a commercial pilot who worked a seven-days-on, seven-days-off schedule. When the original parenting plan was entered, the father had to commute from Spokane to Seattle for work, so the plan was written to begin his parenting time on his second day off and end on his last day off—giving him five consecutive overnights every two weeks.
The father later changed jobs to a new private air carrier with the same seven-on, seven-off rotation. The key difference: his new commute started on his first workday, not his last day off, which gave him a full seven days off instead of six. He petitioned for a minor modification to add one additional overnight every two weeks, beginning on his first day off instead of his second.
The trial court denied the petition at the adequate cause stage. It calculated that the requested change would add 26 days of parenting time per year—exceeding the 24-day statutory limit. But the court made a critical error: it did not account for summers and holidays in its calculation. Under the existing plan, holidays and summer vacation already adjusted the father’s schedule in ways that could offset the additional day. By ignoring those periods, the court overstated the net change.
Why Did the Court of Appeals Reverse?
The Court of Appeals held that the trial court abused its discretion by failing to consider the impact of the proposed changes on the full yearly schedule, including holidays and summer vacation. The statute says the modification must not exceed 24 full days “in a calendar year,” and the court’s calculation admittedly excluded those periods.
Because the father had made a plausible showing that his proposed schedule would not exceed 24 days when the entire year was considered, the court found this was sufficient to establish adequate cause under the standard set in In re Marriage of Parker, 135 Wn. App. 465 (2006). The Court of Appeals remanded with instructions for the trial court to determine whether the father had demonstrated a substantial change in circumstances—the other prong of the minor modification test that the trial court never reached.
Parenting plan modifications involve technical calculations and strict procedural requirements. Blair & Kim’s family law attorneys handle custody and parenting plan matters throughout King, Pierce, and Snohomish Counties, including in Bellevue and Kirkland. Reach out to discuss your case.
Key Lessons for Parents Seeking a Schedule Change
1. The 24-Day Calculation Covers the Entire Calendar Year
The McCormick decision makes clear that courts must consider the full calendar year—including holidays and summer vacation—when calculating whether a proposed change exceeds 24 days. A modification that appears to add 26 days on a simple biweekly basis may actually fall within the limit once holiday rotations and summer schedules are factored in. If you are preparing a minor modification petition, your declaration should include a detailed day-by-day calculation showing how the proposed change plays out across the entire year.
2. A Job Change Can Be a Substantial Change in Circumstances
The father in McCormick argued that his new job and work schedule constituted a substantial change in circumstances. The trial court never ruled on this issue, and the Court of Appeals declined to decide it for the first time on appeal. But the case suggests that a genuine change in employment—particularly one that affects a parent’s availability to spend time with their child—can satisfy the threshold. The change must be real and meaningful, not a pretext for relitigating custody.
3. Adequate Cause Is a Threshold—Not a Final Ruling
The adequate cause determination under RCW 26.09.270 is a gatekeeper function. The court reviews the petition and supporting affidavits to determine whether the petitioner has set forth specific factual allegations that, if proven, would permit modification. It is not a trial on the merits. The McCormick court emphasized that a “plausible showing” is enough to get past the adequate cause stage—the petitioner does not need to conclusively prove the 24-day limit is satisfied at this early stage.
4. Courts Will Not Decide Issues for the First Time on Appeal
The mother in McCormick asked the appellate court to affirm on the alternative ground that the father failed to show a substantial change in circumstances. The court declined, noting that the trial court never made that determination. This is a recurring principle in Washington appellate law: issues not decided below will not be decided for the first time on appeal. It underscores the importance of getting the trial court to rule on each element of the modification test.
Navigating Parenting Plan Modifications in Washington
Whether you are seeking more time with your child or responding to a petition that would change your existing schedule, the minor modification process under RCW 26.09.260(5) requires careful preparation. The 24-day calculation is more complex than it appears—particularly when the parenting plan includes irregular work schedules, rotating holidays, or summer vacation provisions. A miscalculation at the adequate cause stage can result in a denial that delays the process by months.
The attorneys at Blair & Kim, PLLC have extensive experience with family law matters including parenting plan modifications, custody disputes, and child support. With offices in Seattle and Bellevue, the firm serves families throughout King County, Pierce County, and Snohomish County.
Every case is different. Past results do not guarantee a similar outcome. If you need to modify a parenting plan or are responding to a modification petition, contact Blair & Kim today at (206) 622-6562 or submit a confidential inquiry online.