Where do I enter additional 2017 Federal tax Payment paid in 2018 in tax form?

[JulieCo]

You do not record federal tax payments for years other than the year you are filing on your tax return.  Therefore, you would only enter 2018 federal tax payments made on the 2018 return.

You can enter state tax payments made for other years because those amounts can be included as a deduction if you itemize.