Even the head of HHS has the power, I believe, to change the wording of the law as she sees fit
Forbes contributor Jeffrey Dorman notes that a recent ruling in a case involving the Environmental Protection Agency could make it harder for Roberts to conclude that he has that wiggle room.
The power of executing the laws necessarily includes both authority and responsibility to resolve some questions left open by Congress that arise during the laws administration. But it does not include a power to revise clear statutory terms that turn out not to work in practice, Justice Antonin Scalia wrote in an opinion that Roberts joined in full.
I hope he is right
But in crafting PPACA they were careful to give a lot of discretionary power to the director, a point Sebelius (now gone) was happy to chirp about. He successor presumably has the same power though is not so overt about it in public.