How to turn down a tenant I already accepted a holding deposit for

[Samantha Coppinger]

Hi, I was looking for advice. I recently accepted a prospective tenants application for one of my rentals. Originally they said they wanted to move by October 1st. Then after accepting the application, they wanted to change it to the middle of October. I accepted and prorated the amount that would be needed to move in. When meeting for the holding deposit the prospective tenant was 40 min late due to work and not being able to find place to get a money order. We also signed an agreement that if the tenant couldn't move in by the date agreed upon they would forfeit the holding deposit. Just now the tenant has emailed saying that they would like to move in Nov 1st instead, to make sure they have the full amount needed to move in. I let them know that it wasn't what I had agreed to and I would have found someone to move in sooner if that was the case, and would find someone else if they couldn't move in by the date agreed upon. They got back to me and said they would have all the money the evening we agreed upon. However I am no longer confident that this prospective tenant will be able to manage themselves and pay on time. I want to give them their holding deposit back and deny leasing to them. How can I do this in a professional way and what reason do I give them for denying them the rental after I already accepted them?