Furnish a detailed schedule showing the type, nature and source of the income and copy of Federal return. Documents submitted should reflect to which state(s) the income is attributable. Enclose the other state's return and/or Schedule K-1, if applicable.
If you are mailing your return, be sure to include this information with your return. If you are e-filing your return, retain the information in your records for three years in case the Oklahoma Tax Commission requests it.