Essential Business Tax Deadlines for December 2025

December is a critical month for businesses, with significant tax deadlines requiring attention, such as corporate estimated tax payments and monthly payroll tax deposits. Additionally, this is your last chance to finalize any year-end financial actions ahead of the December 31st closures.

December 15 - Corporations

The deadline for the fourth installment of estimated tax payments for corporations operating on a calendar year is due on December 15, 2025. Timely payments help avoid interest and penalties.

December 15 - Social Security, Medicare, and Withheld Income Tax

If the monthly deposit rules apply to you as an employer, this is the due date to deposit November's Social Security, Medicare, and withheld income tax. The same applies to nonpayroll withholding under the monthly deposit rule for November 2025.

December 31 - Plan Ahead for Year-End

December 31 marks the final day to execute any outstanding financial actions. Given some financial institutions may be closed, consider completing transactions earlier to avoid potential disruptions.

Weekends & Holidays:

If a tax deadline falls on a weekend or legal holiday, the due date rolls over to the next business day, provided it is not also a holiday.

Disaster Area Extensions:

For disaster-designated areas, tax deadlines can be extended. For updates on disaster declarations and extensions, visit FEMA: FEMA Disaster Declarations and the IRS: IRS Tax Relief in Disaster Situations.

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