Please fill out the form below or see additional contact information below this form. How do I sign up for Nassau Financial Online Banking?Having the payoff letter and proof of payment will take care of the issue if you try to sell and the mortgage is open. Customer. SmartAsset's New York paycheck calculator shows your hourly and salary income after federal, state and local taxes. 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. Most forms may be filled out on your computer, printed and submitted for filing with the Department of State. After this date, please request a new payoff letter.