How do I fill this out? Form 1098 is used to report mortgage interest and related expenses paid for the year.Cook County Mortgage Form. Fill in the blank form formatted to comply with all recording and content requirements. Names on Certificate must include the Lender and, at minimum, one of the Borrowers listed on the Mortgage. Document. 2. You can complete these copies online for furnishing statements to recipients and for retaining in your own files. Specific Instructions. Cook County Mortgage Form. Fill in the blank form formatted to comply with all recording and content requirements. Customer: I receive a mortgage statement in the mail monthly and pay the amount due as scheduled.