(a) If an employee who has a permanent impairment incurs a subsequent injury or disease arising out of and in the course of employment, which subsequent injury results in liability for the disability arising from merger of the subsequent injury with the preexisting permanent impairment, the employer or insurer shall in the first instance pay all compensation provided by this chapter. The employer or insurer shall be reimbursed from the Subsequent Injury Trust Fund for all weekly income benefits payments payable after 104 weeks of payment.

(b) An employer or insurer who has paid medical and rehabilitation expenses on behalf of the employee who comes under this article shall be entitled to reimbursement from the fund on the following basis:

(1) Fifty percent reimbursement of all medical and rehabilitation expenses which exceed $5,000.00 but do not exceed $10,000.00;

(2) One hundred percent reimbursement of all medical and rehabilitation expenses paid which exceed $10,000.00.

(c) As a prerequisite to reimbursement from the fund, the insurer shall be required to certify that the medical and indemnity reserves have been reduced to the threshold limits of reimbursement.

(d) When the same employer in a claim accepted by the fund for reimbursement returns the injured worker to work with the same employer, the employer shall not be subject to further indemnity or medical deductibles in the event the employee suffers a new accident that merges with the same prior impairment that previously resulted in fund acceptance of the prior reimbursement claim. This provision does not apply if the employee returns to work for a different employer or there has been a break in service by the employee.

(e) As a prerequisite to reimbursement from the fund, there must be evidence of payment of workers' compensation benefits in accordance with Code Section 34-9-221 or an award of the State Board of Workers' Compensation directing the employer to pay weekly income benefits as a result of the subsequent injury.

(f) The fund shall reimburse only those indemnity, medical, and rehabilitation expenses that the employer or insurer was legally obligated to pay to the employee or claimant. The fund shall reimburse such expenses at a rate not exceeding the usual and customary charges. The administrator of the fund may refer any medical or rehabilitation expense to the State Board of Workers' Compensation for review and recommendation and, in the event of a dispute between the fund and the employer or insurer, the questioned medical and rehabilitation expense shall be referred to the State Board of Workers' Compensation for approval. This subsection shall apply to any claim filed against the fund on and after July 1, 1987.