Nothing prohibits non-refundable deposits. These are not uncommon and are used to defray the opportunity cost of a tenant refusing to rent a property after it has been taken off the market.
Mr. Vicary is licensed to practice law in Florida. The response herein is not legal advice and does not create an attorney/client relationship. The response is in the form of legal education and is intended to provide general information about the matter within the question. Oftentimes the question does not include significant and important facts and timelines that, if known, could significantly change the reply and make it unsuitable. Mr. Vicary strongly advises the questioner to confer with an attorney in your state in order to ensure proper advice is received.