Lackay went to the Commission for Conciliation, Mediation and Arbitration seeking maximum compensation for constructive dismissal after resigning in 2015.
His resignation followed a probe by SARS into his role in an alleged rogue investigative unit set up by Finance Minister Pravin Gordhan when he was the commissioner of SARS in 2007.
Lackay plans to argue at the hearing that it became intolerable for him to remain at SARS as his duties had systematically been taken away.