Legal Question in Real Estate Law in Illinois

The good news is that unlike most unmarried couples, it sounds as though you entered into something of a partnership agreement with the main topic being a potential buy-out agreement, so at least there is some protection for you, although without seeing the agreement it's impossible to say for sure. The appraised value may be irrelevant, however, and what you two agree upon with respect to a payment is what will count. So the bad news is that you may have shorted yourself on the "value added". Have an attorney review what you wrote up and, if it does not protect you adequately, you may have to go back to your girlfriend to adjust the agreement, if she's willing. For the kind of money you're talking about, not getting an attorney involved could be a real issue if and when you may have to rely on the agreement you think you have.

It depends on the terms of your agreement. Does the agreement specify if equity is based on the assessed value, appraised value, purchase price plus improvements? If not, and you cannot agree, you may need to let a judge decide for you, which may cost you a good portion of that equity. Most of the mortgage payments you have made went to interest, so unless you have been there for a good length of time, I would not expect much equity to have built up from those.