Hit the nail on the head. We have a progressive income tax here. The 20% comes from the part of my salary that gets the higher tax bracket. So in fact the decr

Hit the nail on the head. We have a progressive income tax here. The 20% comes from the part of my salary that gets the higher tax bracket. So in fact the decrease in amount I get paid is quite a bit less than 20%. I also suggested this change at the yearly salary interview during which I negotiated a 10% raise. So really the amount I get paid each month didn't change all that much.