It can be a 2023 Estimated payment OR an extension payment for 2024. Be sure to use the right form 1040ES or pay online and select 2023. The four 1040ES quarterly estimates for 2023 are due
April 18, 2023
June 15, 2023
Sept 15, 2023
Jan 16, 2024
Thank you. Was just taking a look at my taxes and got a little turned around in my head. I'm good now thanks for the help
When [you] make an estimated tax payment on January 15 [ or 18 if any holidays], 2024,
that is the last day to make your timely fourth quarter estimated tax payment for 2023.
Still you must designate the tax year, either with the voucher, or at the setup of your online payment.
If you send a check, write "For <tax year>" on the check.