If you make 300,000,- kr a year living in the region of Køge, Denmark, you will be taxed 102,147, kr. That means that your net pay will be 197,853,- kr per year, or 16,488,- kr per month. Your average tax rate is 34.1% and your marginal tax rate is 40.1%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100,- kr in your salary will be taxed 40.14,- kr, hence, your net pay will only increase by 59.86,- kr.
A 1,000,- kr bonus will generate an extra 599,- kr of net incomes. A 5,000,- kr bonus will generate an extra 2,993,- kr of net incomes.