If you make 1,800,000 грн a year living in Ukraine, you will be taxed 351,000 грн. That means that your net pay will be 1,449,000 грн per year, or 120,750 грн per month. Your average tax rate is 19.5% and your marginal tax rate is 19.5%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100 грн in your salary will be taxed 19.50 грн, hence, your net pay will only increase by 80.50 грн.
A 1,000 грн bonus will generate an extra 805 грн of net incomes. A 5,000 грн bonus will generate an extra 4,025 грн of net incomes.