Massachusetts, California, New York, New Jersey and Hawaii impose top rates above 9% to 13%, often kicking in around $1 million of income.
The extra levies sit on top of existing income taxes and can sharply raise bills on business sales, stock options and other one-off capital gains.
Supporters present the policy as fair, targeted revenue-raising, while critics say it penalises success and may encourage wealthy residents and business owners to move.
As 'millionaire taxes' spread, are states risking their economies by driving away the high-earners they aim to tax?
If state surtaxes prove effective at raising revenue, could a national 'millionaire tax' become a reality under current federal leadership?