September 10, 2024

Individuals – Report August tip income of $20 or more to employers (Form 4070).

September 16, 2024

Individuals – Pay the third installment of 2024 estimated taxes (Form 1040-ES), if not paying income tax through withholding or not paying sufficient income tax through withholding.

Calendar-year corporations – Pay the third installment of 2024 estimated income taxes, completing Form 1120-W for the corporation’s records.

Calendar-year S corporations – File a 2023 income tax return (Form 1120-S) and provide each shareholder with a copy of Schedule K-1 (Form 1120S) or a substitute Schedule K-1 if an automatic six-month extension was filed. Pay any tax, interest and penalties due.

Calendar-year S corporations – Make contributions for 2023 to certain employer-sponsored retirement plans if an automatic six-month extension was filed.

Calendar-year partnerships – File a 2023 income tax return (Form 1065 or Form 1065-B) and provide each partner with a copy of Schedule K1 (Form 1065) or a substitute Schedule K1 if an automatic six-month extension was filed.

Employers – Deposit Social Security, Medicare and withheld income taxes for August if the monthly deposit rule applies.

Employers – Deposit nonpayroll withheld income tax for August if the monthly deposit rule applies.

Calendar-year trusts and estates – File a 2023 income tax return (Form 1041) if an automatic five-and-a-half-month extension was filed. Pay any tax, interest and penalties due.