Okla. Stat. tit. 40, § 1-227
"Experience period" means the most recent twelve (12) consecutive completed calendar quarters occurring before July 1 of the year immediately preceding the year for which the employer's contribution rate is being calculated.
Laws 2006, SB 1634, c. 176, § 4, emerg. eff. July 1, 2006; Amended by Laws 2017, HB 1110, c. 345, § 1, emerg. eff. July 1, 2017 (superseded document available).