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.
@craiganderson27
