First Mortgage A mortgage registered before all others on title. Gives the lender a primary lien/charge against your house and property that has precedence over all other mortgages. Priority is determined by the date and time registered, so a first mortgage was literally and legally registered \"first\". A new first mortgage can therefore only be registered as a \"first\" mortgage upon the discharge of an existing one if the holder of a second mortgage \"postpones\" (i.e., \"puts back in time\") to a time immediately following the registration of the new first mortgage.