Corporate Tax Extension Reference (2026)

C-Corp Form 1120 • All 50 States + DC + Major Local Jurisdictions • Verified March 2026

IRC §6081 Form 7004 Treas. Reg. §1.6081-3 59 Jurisdictions

Universal rule: An extension of time to FILE never extends the time to PAY. Tax owed is due by the original due date in all jurisdictions. Interest and failure-to-pay penalties accrue from the original due date on any unpaid balance. Federal Form 7004 provides an automatic 6-month extension for calendar-year C-Corps: April 15 → October 15. Treas. Reg. §1.6081-3(a) grants the automatic 6-month extension to C corporations, and the Instructions for Form 7004 and IRM 3.12.212 apply it to December 31 year-ends. The text of IRC §6081(b), as amended by Pub. L. 114-41 §2006(c), substitutes 5 months for December 31 C corporation years beginning before January 1, 2026, but IRS administration (Form 7004 instructions; IRM 3.12.212) treats December 31 C corporations as receiving 6 months. Exception: C corporations with a June 30 year-end beginning before January 1, 2026 receive 7 months (Reg. §1.6081-3(e)); for years beginning in 2026 the period is 6 months.

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Jurisdiction ↕	Type ↕	Category ↕	Form Required	Length	Payment w/ Extension	Primary Citation	Notes

Source: tk.cpa Corporate Extension Matrix (verified March 2026). Federal: IRC §6081; Treas. Reg. §1.6081-3; Form 7004 Instructions. State citations as noted per row. Scope: C-Corp (Form 1120) only. S-Corp (1120-S) and Partnership (1065) rules differ in many states. Local jurisdictions: NYC BCT/GCT, Detroit City CIT, Philadelphia BIRT, San Francisco GRT, Los Angeles LACBT, Portland/Multnomah BLT/MCBIT, Ohio Municipalities (RITA). Maintained by the tk.cpa AI lab. Always verify current-year form instructions before filing. A tk.cpa resource. tk.cpa is owned & operated by tk.cpa

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