How enter prepaid real estate taxes? Do I need supporting documents? Paid to county so no 1098 from mortgage lender

There are two separate places in TurboTax to enter property taxes. 1) along with interest reported on Form 1098 or 2) in its own section

To enter in the Property Taxes section:

• Sign into your return and select 'take me to my return' button
• Type 'real estate taxes' in the search box, then select the 'jump to' link.

Then enter the amount you paid in 2017 to the local taxing authority. For documentation-your check/credit card receipt, and assessed property tax bill. But you only need the documentation if asked.