Additional principal payment. From the new Servicing Digital Portal, you can access and manage all of your mortgage loan information, and make your monthly payment online!Making extra mortgage payments can help pay off your mortgage early and save money on interest. Does prepaying make sense? The mortgage payoff calculator helps you find out. There's probably an online form. This calculator allows you to enter an initial lump-sum extra payment along with extra monthly payments which coincide with your regular monthly payments. Paying Extra On Your Mortgage Principal Payments? Paying Extra On Your Mortgage Principal Payments? This calculator allows you to enter an initial lump-sum extra payment along with extra monthly payments which coincide with your regular monthly payments.