Oklahoma Filing Due Date: Corporation tax returns are due by March 15 — or by the 15^th day of the 3^rd month following the end of the taxable year (for fiscal year filers).

Extended Deadline with Oklahoma Tax Extension: For an extension of time to file the Oklahoma corporation return, the extension period may not exceed 7 months. Businesses that have a valid Federal tax extension (IRS Form 7004) will automatically be granted an Oklahoma tax extension for the same amount of time.

Oklahoma Tax Extension Form: To request an Oklahoma-only tax extension, file Form 504 by the original deadline of your return. Form 504 should only be used if you don’t have a Federal extension or if you need to make an Oklahoma extension payment.

If you have an approved Federal extension (IRS Form 7004), you will automatically be granted an equivalent Oklahoma tax extension.

Oklahoma Extension Payment Requirement: An extension of time to file is not an extension of time to pay. You must pay your Oklahoma tax balance by the original due date to avoid late fees. In order to obtain an Oklahoma tax extension, at least 90% of your tax liability must be paid by the original deadline. You can make your Oklahoma extension payment with Form 504, or pay electronically via Oklahoma Online Services: www.tax.ok.gov/payments

Oklahoma Tax Extension Tips: Do not use Form 504 if you electronically submit your Oklahoma extension payment.

When you file your Oklahoma tax return, make sure to attach a copy of your tax extension request (IRS Form 7004 or Oklahoma Form 504).