Ohio Rev. Code § 4123.522
The employee, employer, and their respective representatives are entitled to written notice of any hearing, determination, order, award, or decision under this chapter and the administrator of workers' compensation and his representative are entitled to like notice for orders issued under divisions (C) and (D) of section 4123.511 and section 4123.512 of the Revised Code. An employee, employer, or the administrator is deemed not to have received notice until the notice is received from the industrial commission or its district or staff hearing officers, the administrator, or the bureau of workers' compensation by both the employee and his representative of record, both the employer and his representative of record, and by both the administrator and his representative.
If any person to whom a notice is mailed fails to receive the notice and the commission, upon hearing, determines that the failure was due to cause beyond the control and without the fault or neglect of such person or his representative and that such person or his representative did not have actual knowledge of the import of the information contained in the notice, such person may take the action afforded to such person within twenty-one days after the receipt of the notice of such determination of the commission. Delivery of the notice to the address of the person or his representative is prima-facie evidence of receipt of the notice by the person.
R.C. §4123.522