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:
To enter your qualifying mortgage insurance premiums as an Itemized Deduction, please follow the steps below:
At this time, the IRS Publication does still indicate that home mortgage insurance premiums are not deductible, but includes the following disclaimer: "At the time this publication went to print, the itemized deduction for mortgage insurance premiums and the credit for nonbusiness energy property had expired. You can’t claim a deduction for these expenses paid or incurred after 2016. To find out if legislation extended these deductions so you can claim them on your 2017 return, go to IRS.gov/Extenders."
Per IRS Publication 530 Tax Information for Homeowners, page 2:
Nondeductible payments. You can’t deduct any of the following items.