A biweekly mortgage payment plan is a formal method of prepaying your mortgage. Under a biweekly payment schedule, you make a payment on your mortgage every two weeks instead of once a month. Each of these payments is roughly equal to one-half of a normal monthly payment. By making biweekly payments, you end up making an extra payment over the course of each year (26 half payments are equal to 13 full payments). You also pay less interest in the long term, because payments are applied to your principal balance more frequently.