File Oklahoma Form 504-C for Your Business Tax Extension

You generally need Form 504-C when you owe additional Oklahoma income tax, do not have a federal extension, or need additional time beyond the federal extension. When there is no additional Oklahoma tax due, Oklahoma honors the automatic federal extension and requires a copy of the federal extension with the Oklahoma return.

Oklahoma administratively honors the automatic federal extension when no additional Oklahoma tax is due. When filing the Oklahoma return, you must provide a copy of the federal extension. If additional Oklahoma tax is due, or you need an extension beyond the federal extension, use Form 504-C.

No. Form 504-C extends the time to file, not the time to pay. At least 90% of the tax liability must be paid by the original due date for the extension to be valid. A 5% delinquent penalty may apply if at least 90% has not been paid by the original due date, and interest of 1.25% per month may apply if the full tax liability has not been paid.

Yes. Oklahoma accepts an electronic extension payment through its online payment system. A convenience fee may apply to some electronic payment services. If you make the extension payment electronically, do not mail Form 504-C. Provide a copy of Form 504-C when you file your Oklahoma income tax return.

For partnerships and fiduciaries, the extension cannot exceed one-half of the accounting period covered by the return, such as a 6-month extension for a 12-month tax year. For corporate returns, the extension may not exceed 7 months.

If you are mailing Form 504-C with payment, if applicable, send it to:

Oklahoma Tax Commission
PO Box 26890
Oklahoma City, OK 73126-0890