I was about to rent an apartment in Austin Texas and I gave the landlord 500.00 for a deposit. I have not signed the lease yet and changed my mind. Can they keep that deposit? They ared saying 250.00 was because I had bad credit.

It depends very likely they can keep at least half if not all. Did he give you a paper that state his agreements/rules?

What did you sign when you gave them the money, often there is a applicatin fee, a credit fee and so on. What did the receipt you were given say about the money