Alimony paid can be entered on a 2018 tax return as an Adjustment to Income provided that the divorce occurred on or before 12/31/2018.  Alimony received also must be reported on a tax return if the divorce occurred before 12/31/2018.

See this TurboTax support FAQ for the tax code changes - https://ttlc.intuit.com/questions/4482394-how-will-tax-reform-affect-my-2018-federal-tax-return

To enter alimony paid -

• Click on Federal Taxes (Personal using Home and Business)
• Click on Deductions and Credits
• Click on I'll choose what I work on (if shown)
• Scroll down to Other Deductions and Credits
• On Alimony Paid, click the start or update button

Or enter alimony paid in the Search box located in the upper right of the program screen.  Click on Jump to alimony paid

Alimonies for divorces and separations finalized after 2018 are no longer taxable or deductible.