Section 440.(a) In any contested case where the insurer has contested liability in whole or in part, including contested cases involving petitions to terminate, reinstate, increase, reduce or otherwise modify compensation awards, agreements or other payment arrangements or to set aside final receipts, the employee or his dependent, as the case may be, in whose favor the matter at issue has been finally determined in whole or in part shall be awarded, in addition to the award for compensation, a reasonable sum for costs incurred for attorney's fee, witnesses, necessary medical examination, and the value of unreimbursed lost time to attend the proceedings: Provided, That cost for attorney fees may be excluded when a reasonable basis fold the contest has been established by the employer or the insurer.
(b) If counsel fees are awarded and assessed against the insurer or employer, then the workers' compensation judge must make a finding as to the amount and the length of time for which such counsel fee is payable based upon the complexity of the factual and legal issues involved, the skill required, the duration of the proceedings and the time and effort required and actually expended. If the insurer has paid or tendered payment of compensation and the controversy relates to the amount of compensation due, costs for attorney's fee shall be based only on the difference between the final award of compensation and the compensation paid or tendered by the insurer.