In Washington state, it is best to have a written lease. Oral leases are valid, but they can be enforced only as leases from month to month. A lease for longer than month to month must be in writing. Per RCW § 59.04.010, if the lease is longer than one year, the execution of the lease must be acknowledged (i.e. notarized).

If a lease is longer than one year and it is not acknowledged, then it may be interpreted to be only a month to month lease, not a one-year lease. This may also apply to unacknowledged one-year leases with any options to renew.

To summarize, it is the best practice to do the following in Washington:

  1. Always have a written lease.
  2. For any lease longer than one year, acknowledge (notarize) the signatures of both parties.
  3. For any lease one-year or less that has renewal options that would extend the term of the lease beyond one year, acknowledge (notarize) the signatures of both parties.