Summary
If you make 3,900 kr a year living in the region of Roskilde, Denmark, you will be taxed 1,699 kr. That means that your net pay will be 2,201 kr per year, or 183 kr per month. Your average tax rate is 43.6% and your marginal tax rate is 32.3%. 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 32.28 kr, hence, your net pay will only increase by 67.72 kr.
Bonus Example
A 1,000 kr bonus will generate an extra 677 kr of net incomes. A 5,000 kr bonus will generate an extra 3,386 kr of net incomes.