Why not 120% ?
Simply murder them and confiscate their worldly goods.
Pretty much what the Paris Commune did during the height of the French Revolution.
That worked so well then.
And of course they saw to it that it was all perfectly legal.
And why $425,000? That’s more than enough to live on. Hell. $100,000 is enough to live on. Make the tax 100% on all income above $100,000.