This is a common occurrence but the answer is not easily identifiable, how much will depend on many factors related to the expenses incurred during the ownership and whether or not the parties can agree on a number or if we need to get a Judge to determine the correct number. The issue for you is that if he is on title you may not be able to sell the home without coming to an agreement with your co-owner. I recommend that you contact a real estate litigation attorney to help you in determining what is fair and to assist you in negotiating a resolution. If your co-owner is uncooperative or unreasonable then you will likely need to bring a lawsuit to resolve this.