Tenant last month rent

[Goran Kocev]

So there is this tenant everything was ok till now but lease expires end of this month they have not pay rent for this month and insist the deposit is used for that , the problem is the deposit is there for security when they move out and they still have to pay for this month and get refund on the deposit when they move out minus bills and damages .

First time handling this kind of situations , any experience sharing would help