It does not matter what the President calls it, the Supreme Court ruled that the provision can ONLY be upheld if it is a tax. It then upheld the ruling. This is a de facto declaration of a tax by the Court.
To borrow a phrase from Nancy Pelosi, it was *deemed* a tax. Ironically, Nancy Pelosi, House sponsor of the bill, had authority to declare it a tax but did not. She is on public record as stating that this provision is NOT a tax. It is her stated opinion that this provision drew its authority through the commerce clause.