Deadline for employees who received $20 or more in tips during August to report them to their employers using Form 4070.
September 15, 2026
Q3 Estimated Tax Payment Due: Third-quarter estimated tax payments for 2026 (Form 1040-ES) are due for self-employed individuals and gig workers.
Extended Partnership & S-Corp Returns: Final deadline to file extended income tax returns for calendar-year partnerships (Form 1065) and S-corporations (Form 1120-S).
Employer Payroll Deposits: Deposit Social Security, Medicare, and withheld income taxes for August if the monthly deposit rule applies.
September 30, 2026
Extended due date for Form 1041 (Income Tax Return for Estates and Trusts).











