Before you can raise the rent, you have to give the tenant written notice a set number of days ahead of time. This tool counts backward from the date you want the new rent to start and tells you the last day you can legally serve that notice.
Seattle requires 180 days' written notice for any housing-cost increase, and housing costs can include recurring charges like parking or storage, not just base rent. That's roughly six months, far longer than most landlords expect. The day you serve and the day the new rent starts don't count toward the 180, and a deadline that lands on a weekend or holiday does not move, so this tool counts the careful way the city's own example does.
Everywhere else in Washington the baseline is 90 days (raised from 60 by House Bill 1217 in 2025). Serving notice even a day late means the increase can't take effect on your target date: you have to push it out.
If you serve the notice by mail rather than in person, Washington adds 5 days before the clock starts, so the tool also shows an earlier “mail by” date. It flags two other things while it's at it: whether your increase exceeds the statewide rent cap, and whether it's large enough to trigger Seattle's EDRA relocation-assistance rules.
Where this comes from
A few facts about the lease and the increase you have in mind:
Jurisdiction. Seattle or the rest of Washington. This sets the notice length: 180 days inside Seattle, 90 days elsewhere.
Tenancy start date. When this tenant moved in. Washington bars any rent increase during the first 12 months, so the date confirms your increase is even allowed yet.
Current monthly rent. The rent in force today. Used with the new rent to check the increase against the rent cap and EDRA thresholds.
Planned new monthly rent. What you intend to charge. The notice deadline doesn't depend on the amount, so you can leave this blank while you're deciding; add it to also check the rent cap and EDRA threshold.
Target effective date. The day you want the new rent to begin. Every deadline is counted backward from this date.
That's GiveProperNotice: one calendar for every unit, every rule change handled for you, for $99 a year.
Not sure your increase is under the legal ceiling first? Check the rent cap.
Neither one counts. Seattle's own worked example excludes both ends, and this tool counts the same careful way.
It does not move. A deadline that falls on a Saturday, Sunday, or holiday stays where it is, so plan to serve earlier rather than assuming a rollover.
Yes. Washington adds 5 days before the notice clock starts when you serve by mail rather than in person, so the mail-by date is earlier than the in-person date.
In Seattle it covers housing costs, which can include recurring charges like parking or storage, not just base rent.
