At the beginning, you earn 1800€ (basic salary) + 100€ (bonus), i.e. 1900€ gross plus an additional 173€ net (120€ expenses + 9€ laundry allowance + 44€ non-cash voucher). With tax class 1 without children you get 1547,79€ net per month. Tax class 3, without children would be 1690,62€ or with two children 1695,37€.