You only have to tell the renter which bank, and which branch of which bank. Probably safer to open it as a trust account. Any interest you earn is yours.
When you take a deposit, you have to have a written agreement and that agreement has to have a walk through checklist detailing the condition of the property at the beginning of the tenancy. In addition to this checklist, pictures would be really handy.
The deposit rules are at RCW 59 8 260, 270 and 280. Elizabeth Powell
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Separate account. It takes little to do this and you will very likely be far happier for having done so if things don't work out for you in this rental. As a small aside, the state of our economy at this time has resulted in many of these "room rent" arrangements....and lately a great deal of my practice has involved hybrid matters of Protection Orders and unlawful detainers taking place simultaneously. I strongly recommend you take some time to read up on landlord obligations before you take someone in under your own roof and I would also suggest that you informally become acquainted with an attorney who represents landlords in your area in case odd things start happening once your tenant is in. Good luck.