I don’t know if it’s still true or true in such a huge number, but in California the lotto winnings are (or were) exempt from state taxes. Which is a whopping 13.9%+ So, if a Californian wins, they just pay the Federal top rate.
Of course, I’d take the lump sum vs the 30 year installment so it’s probably more like $450 million. $600 million lump sum less apx 24% federal tax.
Best count on paying 37% in taxes…