Okla. Stat. tit. 36, § 36-4106: Group annuity; grace period

In group annuity contracts there shall be a provision that there

shall be a period of grace, either of thirty (30) days or of one (1)

month, within which any stipulated payment to be remitted by the

holder to the insurer, falling due after one (1) year from date of

issue, may be made, subject, at the option of the insurer, to an

interest charge thereon at a rate to be specified in the contract,

which shall not exceed six percent (6%) per annum for the number of

days of grace elapsing before such payment.