A Satisfaction of Security Instrument is a document that shows an individual has paid a deed of trust or a mortgage in full. Depending on your lender, you may have to sign in to an online account, call a helpline, or send a formal letter to start the request process.A payoff request can be created and mailed for free. How long does it take to obtain a payoff? Designed to protect the privacy and rights of the borrower, the form requires detailed information and authorization to release the loan payoff details. A letter of explanation can be important in the mortgage underwriting and application process. A Payoff Request Form is an essential document for those looking to fulfill the remaining balance on a home equity line of credit.