Individuals: Paying the third installment of 2023 estimated taxes, if not paying income tax through withholding (Form 1040-ES).

Calendar-year corporations: Paying the third installment of 2023 estimated income taxes.

Calendar-year S corporations: Filing a 2022 income tax return (Form 1120-S) and paying any tax, interest and penalties due, if an automatic six-month extension was filed.

Calendar-year S corporations: Making contributions for 2022 to certain employer-sponsored retirement plans, if an automatic six-month extension was filed.

Calendar-year partnerships: Filing a 2022 income tax return (Form 1065 or Form 1065-B), if an automatic six-month extension was filed.