Upon receiving a claim for benefits from an injured worker, the Administrator shall promptly investigate the claim and begin payment of benefits within twenty-one (21) days of a valid claim or the Administrator shall send the claimant written notice within twenty-one (21) days, that further investigation is needed and the reasons for further investigation. The Administrator shall complete its investigation within forty-five (45) days of receipt of the claim and shall commence the payment of benefits or notify the claimant in writing that the claim is denied. ONCA 12-76, eff. Oct. 1, 2012.