1. The amount of money in an account, equal to the net of credits and debits at that point in time for that account. also called account balance. 2. The amount remaining to be paid toward an obligation. For example, a homeowner who has paid down $25,000 of a $100,000 mortgage has a principal balance of $75,000. Balance also refers to the appraisal principle that states the greatest value in a property will occur when the type and size of the improvements are proportional to each other as well as the land.