Department of Social Development director general Zane Dangor has resigned from his position.
Dangor confirmed to News24 on Saturday that he tendered his resignation on Friday.
He said it was essentially a breakdown in the relationship between himself and the minister over disagreements on Sassa's legal obligations to the Constitutional Court.
He did not want to comment on whether he thought he had been treated fairly on the Sassa matter.
Dangor was appointed director general in November 2016, after his predecessor left the department.
He had been special adviser to the minister before that since 2010, according to the department's website.
He could not confirm if Social Development Minister Bathabile Dlamini had received his resignation yet.
Department spokesperson Lumka Oliphant could not be immediately reached on Saturday morning. News24