3 roommates, 1 moving out, re-newing lease - dealing with deposit

[Peter Hroph]

Appreciate in advance for advice. 

I plan to re-new lease but unsure how to deal with deposit and last month's rent. I have 3 great tenants who are roommates - who also paid last month's and deposit in '15. One of them is moving out, and 2 remaining will be staying. I only get one check from them on monthly basis, they divide amount between each other, equally.

Oct 1 is the date when lease expires. Instead of 'returning' deposit from '15, and having two remaining write new check, can anyone suggest wording/letter that I could have the moving out tenant sign stating something along the lines of 'I, ____, have received my full deposit back, including interest, from my roommates Xname and Zname and do not expect any additional monetary return from my landlord, _____' ? 

Should I deal with it differently? They are nice young working professionals, and I have no doubt they will, if not already, return their deposit share back to the leaving tenant. However, I would like to protect myself.

[Mike Wood]

@Peter Hroph I dont know why you are considering even given them the deposit back for a lease renewal.  I have rented to college students that swap tenants, and I informed them that the deposit is to be worked out between themselves, and I am NOT returning any deposit for a renewal.  If one moved out and they did not have another roommate, would you accept 2/3 of the deposit? No, you would not.  You ask for one rent check, its not up to you to decide who pays what, just that the rent is paid in full. 

How I would personally handle it is to tell them no deposit will be return until the unit is vacated by everyone. If they dont like that, you can redo the entire lease, return the entire deposit, increase the rent and the security deposit, and have them sign an entire new lease.

I tell me tenants that are roommates that I collect the full rent, how they get it is up to them.  I dont take partial rent payments, so if one roommate cant pay rent, everyone gets evicted.  Might sound harsh, but I dont need roommate drama as a landlord.