To initiate this process, kindly have the authorized borrower complete and submit a payoff authorization form to our loan servicing department. A mortgage payoff letter can come in two forms.One form tells borrowers the remaining principal amount and interest they have to pay to close out the loan. San Antonio, TX 78269-2408. Or Fax to (866) 493-1441. Have a Question about an Existing Loan? Need to make a payment, request a payoff amount, etc? For mortgages in San Antonio, Jefferson Bank has you covered with conventional, VA and FHA loans, down payment help and first-time homebuyer programs. SWBC Mortgage Corporation and our team of mortgage loan experts are here to help you find the happiest way home. Sign in online or through your mobile device to schedule fast and secure payments with no fee.