Okla. Stat. tit. 40, § 2-603
The claimant or any other party entitled to notice of a determination may file an appeal from such determination with the appeal tribunal within ten (10) days after the date of mailing of the notice to his last-known address or, if such notice is not mailed, within ten (10) days after the date of delivery of such notice.
Laws 1980, SB 637, c. 323, § 2-603, eff. October 1, 1980.