Per the IRS Instructions for Schedule A (Form 1040), starting on page 8:
Mortgage Insurance Premiums
Enter the qualified mortgage insurance premiums you paid under a mortgage insurance contract issued after December 31, 2006, in connection with home acquisition debt that was secured by your first or second home. Box 5 of Form 1098 shows the amount of premiums you paid in 2017. If you and at least one other person (other than your spouse if filing jointly) were liable for and paid the premiums in connection with the loan, and the premiums were reported on the other person's Form 1098, report your share of the premiums on line 13. See Prepaid mortgage insurance premiums, later, if you paid any premiums allocable to any period after 2017.
Qualified mortgage insurance is mortgage insurance provided by the Department of Veterans Affairs, the Federal Housing Administration, or the Rural Housing Service (or their successor organizations), and private mortgage insurance (as defined in section 2 of the Homeowners Protection Act of 1998 as in effect on December 20, 2006). Mortgage insurance provided by the Department of Veterans Affairs and the Rural Housing Service is commonly known as a funding fee and guarantee fee, respectively. These fees can be deducted fully in 2017 if the mortgage insurance contract was issued in 2017. Contact the mortgage insurance issuer to determine the deductible amount if it isn't included in box 5 of Form 1098.
Limit on amount you can deduct. You can't deduct your mortgage insurance premiums if the amount on Form 1040, line 38, is more than $109,000 ($54,500 if married filing separately). If the amount on Form 1040, line 38, is more than $100,000 ($50,000 if married filing separately), your deduction is limited and you must use the Mortgage Insurance Premiums Deduction Worksheet to figure your deduction.