Okla. Stat. tit. 40 § 3-121
If a Professional Employer Organization, or PEO, chooses the option to file quarterly tax returns under the account assigned to its client pursuant to paragraph 2 of subsection A of Section 3-120 of this title, and if the client has an experience history from a previous account assigned to that client that can be used in calculating an earned tax rate pursuant to the provisions of Article 3, Part 1, of the Employment Security Act of 1980, then that experience history shall be transferred to the account assigned to that client as a coemployer of that PEO. In addition, if taxable wages were reported by a client in a previous account of the client within the calendar year in which the PEO coemployer account is set up, then the PEO coemployer account shall be given credit for the taxable wages paid on each employee in the immediately previous account under which client wages were reported.
Okla. Stat. tit. 40, § 3-121