I have yet to see an example about net pay decreasing with marginal tax rate increase. When you earn 120k, only those 20k over 100k will be taxed with the higher rate, not the amount below 100k, so every increase in gross salary leads to increase to net salary.
If you include welfare state benefits (which have wage-income-based phaseouts) in income, it's not hard to produce such examples. http://mises.org/daily/3822 has a simple case which has >100% effective marginal rates between about 20k and 50k for a family with one adult and 2 kids.
_That_ is the sort of thing that could go away with a guaranteed basic income. At that point, you'd just have taxes, which do in fact behave as you describe.
The US AMT can have that punitive effect, because AMT is an alternative calculation, not a marginal calculation. Yeah, not marginal, but it is a common tax system.
And there are some programs that don't have marginal phaseouts. Each one is trifilingly small, but they may add up.
Even programs with marginal phaseouts can end up adding up to the phaseout being > 100% of the income (e.g. 10 programs, each of which marginally phases out 11 cents on the dollar).
