Per the IRS page Update on Extender Legislation:
The Budget Bipartisan Act of 2018 was signed Feb. 9 and retroactively extended and modified numerous tax provisions covering 2017. The IRS is incrementally updating the needed forms, and completing programming and testing of our processing systems to reflect each provision of the legislation.
Taxpayers may now file tax returns claiming the following:
Mortgage insurance premiums. The itemized deduction for mortgage insurance premiums expired on December 31, 2016.
CAUTION! At the time this publication went to print, Congress was considering legislation to extend the itemized deduction for mortgage insurance premiums. To find out if this legislation was enacted, and for more details, go to IRS.gov/Extenders.