Section 263. Determination of Disability Rating

   When the employee is no longer receiving weekly benefits under O.C.G.A. 34-9-261 or 34-9-262, and a permanent partial disability (PPD) rating has not previously been requested or issued, the employer/insurer shall have thirty days to request, in writing, from an authorized physician, that the employee be rated in accordance with the "Guides to the Evaluation of Permanent Impairment, Fifth Edition," published by the American Medical Association. The employer/insurer shall furnish a copy of the medical report of rating to the employee, and commence payment not later than 21 days after knowledge of the rating. The employer/insurer are presumed to have knowledge of the rating not later than 10 days after the date of the report establishing the rating.