Tools
Tax Deadline Calendar
Every federal deadline a business owner needs to track — laid out as a single timeline so nothing surprises you.
Next Deadline
Q2 Estimated Tax
Date
Jun 15
In
21 days
Thursday, January 15, 2026
Estimated TaxPastQ4 Estimated Tax
Final installment for prior year. Most underpayment penalties trigger here if missed.
Sunday, March 15, 2026
ReturnsPastS-Corp / Partnership Returns
Form 1120-S and 1065 due. Extension to September 15 available.
Wednesday, April 15, 2026
ReturnsPastIndividual & C-Corp Returns
Form 1040 and 1120 due. Also: Q1 estimated tax. Extension to October 15.
Wednesday, April 15, 2026
Estimated TaxPastQ1 Estimated Tax
First installment of current-year estimates due.
Monday, June 15, 2026
Estimated TaxUpcoming · 21 daysQ2 Estimated Tax
Second installment. Six months in, projections should be refining.
Tuesday, September 15, 2026
Estimated TaxQ3 Estimated Tax
Third installment. The most underrated planning quarter.
Tuesday, September 15, 2026
ExtensionsExtended S-Corp / Partnership
Final deadline for extended Form 1120-S and 1065 filings.
Thursday, October 15, 2026
ExtensionsExtended Individual Returns
Final deadline for extended Form 1040 filings.
Friday, January 15, 2027
Estimated TaxQ4 Estimated Tax
Final installment of current-year estimates.
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