Okla. Stat. tit. 63, § 63-1-314
Delayed death certificate
(a) When a death occurring in this state has not been
registered, a certificate may be filed in accordance with
regulations of the State Board of Health. Such certificate shall be
registered subject to such evidentiary requirements as the Board
shall by regulation prescribe, to substantiate the alleged facts of
death.
(b) Certificates of death registered one year or more after the
date of occurrence shall be marked "delayed" and shall show on their
face the date of the delayed registration.