The highest amount of income tax you pay (Reichensteuer) is 47,48% (45% plus Soli). This number is a bit misleading though since the tax rate is a curve that starts at 14% for incomes above 8656 EUR and reaches a plateau of 42% at a yearly income of roundabout 53000 EUR. The highest tax rate only applies to the part of the income that exceeds about 250000 EUR. So the first 8k are tax free, for every EUR above that you pay a tax rate according to the curve and only the part of the income that exceed 250000 EUR pays the full 45%. So if you have a yearly income of 250001 EUR, the 45% get only levied on 1 EUR. It's obvious that the effective tax rate is far lower than 45% for any income that does not massively exceed 250k.

The blue curve in that graph is the nominal tax rate (Grenzsteuersatz) and the green curve the effective rate: https://de.wikipedia.org/wiki/Einkommensteuer_(Deutschland)#...