Income Tax: Extensions
If there is no additional state income tax due and you intend to file within the period granted by the IRS, the Oklahoma Tax Commission will honor the Federal extension. Enclose a copy of the Federal extension with your filed Oklahoma return. An Oklahoma extension form 504 is required when requesting an extension beyond that granted by the IRS, or if you need to make a payment to cover your anticipated tax liability. An extension is valid only if 90 percent of the tax due is paid on or before the original due date of the return. An Oklahoma extension is not an extension of time to pay the tax, it is only an extension of time to file the return.