March 16
Employers: Deposit nonpayroll withheld income tax for February if the monthly deposit rule applies.
Deposit Social Security, Medicare, and withheld income taxes for February if the monthly deposit rule applies.
Calendar-year partnerships: File a 2025 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, or request an automatic six-month extension (Form 7004).
Calendar-year S corporations: File a 2025 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, or file for an automatic six-month extension (Form 7004). Pay any tax due.
March 31
Employers: Electronically file 2025 Form 1097, Form 1098, Form 1099 (other than those with an earlier deadline), and Form W-2G.
April 10
Individuals: Report March tip income of $20 or more to employers (Form 4070).