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Fourth quarter installment for 2025 estimated income tax is due for calendar year-end taxpayers.
April 15
First quarter installment for 2026 estimated income tax is due for calendar year-end taxpayers.
Form 40 corporation income tax return and tax are due for 2025 calendar year-end taxpayers (Note: This date does not apply to a corporation that is a tax-exempt entity or cooperative. See May 15 and September 15.)
May 15
Form 40 corporation income tax return and tax are due for 2025 calendar year-end tax-exempt organizations that are required to report unrelated business taxable income.
June 15
Second quarter installment for 2026 estimated income tax is due for calendar year-end taxpayers.
September 15
Third quarter installment for 2026 estimated income tax is due for calendar year-end taxpayers.
Form 40 corporation income tax return and tax are due for 2025 calendar year-end cooperatives.
November 16
Important Note: Because November 15 falls on a Sunday, any return, tax payment, estimated payment, or other required action is not due until Monday, November 16.
Form 40 corporation income tax return is due for 2025 calendar year-end taxpayers with a federal extension.
December 15
Form 40 corporation income tax return is due for 2025 calendar year-end tax-exempt organizations with a federal extension that are required to report unrelated business taxable income.
