Is “Supertax” a Scrabble word?
Yes
SUPERTAX
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Supertax
noun
1.An additional tax on something that has already been taxed
2.A higher rate of an existing tax