New owner and looking to learn

[Dan Huntzinger]

I recently took the dive and purchased a duplex. I am trying to learn as I go and hoping the community here can help. Is anyone else here a landlord in Washington state? I know some of our rules are slightly different. I have a tenant that I inherited and her lease expires in the end of May. I know I have to give a 60 day notice of her rent change when she moves month to month. To my understanding that can be verbal and Washington state has no law that maxes rent increase. She had a very low rent due to knowing the seller and I am not changing it massively. She is aware that it will be going up, just not the set amount yet as I haven't decided. My question is, would it behoove me to do a written addendum instead to cover myself? I know Washington state tends to cater to tenants.