Washington does not have "annulment" per se. Annulment is actually a religious concept. The legal term is a decree declaring a marriage to be invalid. These are not easy to obtain. You must show that the marriage took place due to fraud, or duress, or that one of the parties (or both) were in some way incapacitated at the time of marriage (or married to someone else). There is no waiting period if both parties agree the marriage was invalid. If one party contests (believes the marriage is valid) then you must wait for a trial date, which can be 11 months in King County.