Okla. Stat. tit. 85A, § 85A-37: Waiver of exemption or exclusion

A. Any employer engaging in any exempted or excepted employment

may at any time waive the exemptions or exceptions as to any

employee or all employees engaged in the employment as the employer

may elect by giving notice of waiver of the exemptions or exceptions

as provided in subsection B of this section.

B. Notice of waiver of exclusion or exemption referred to in

subsection A of this section shall be given in accordance with the

following provisions:

1. Every employer who waives the exclusion or exemption shall

post, and keep posted, in and about the employer's place of business

typewritten or printed notices to that effect in accordance with a

form to be prescribed by the Commission, and the employer shall file

a duplicate of the notice with the Commission; and

2. The notice shall be given at least thirty (30) days before

any injury. However, if the injury occurs less than thirty (30)

days after the date of employment, the notice, if given at the time

of employment, shall be sufficient notice.