Mortgage prepayment refers to paying more than the regular mortgage payments you have agreed to pay in your mortgage contract. If your mortgage gives you prepayment privileges, you can save thousands of dollars in interest charges by paying down your mortgage faster. However, if you have a closed mortgage, your lender will generally require you to pay a charge to make a prepayment that is more than your privileges allow. Prepayment charges can be costly, so it is important to know when they can apply and how they are calculated. Prepayment charges are sometimes called penalties or breakage costs.