Keith Devins posted a link to an OECD Observer article regarding top marginal rates. What is the top marginal rate? I'll try with a simplified example. Paul earns 1000 units a year, he's among the top earners in his country. Regarding taxes, this income can be divided like this:

200	400	...	100
exempted	tax level 1	...	tax level n=top tax level

Paul should pay 400×tax level 1+...+100×tax level n. Considering that tax systems are always more complicated than we hope, there are other factor to be taken in account. The considered article just does this, and we obtain the top marginal rate, which is the tax rate applied on the last slice of your income when you earn more than a lot. Here are the results (figures from 1999):

Country	Top marginal rate	Threshold
USA	40-48%
France	61%	ca. 59,000€
Denmark, Sweden	62%
Japan	65%
Belgium	66%

Disclaimer: I'm neither a lawyer nor an economist (and I was pretty bad when I studied those topics). All feedback welcome kame@cinemasie.com.