If you make ₦1,800,000 a year living in Nigeria, you will be taxed ₦416,421. That means that your net pay will be ₦1,383,579 per year, or ₦115,298 per month. Your average tax rate is 23.1% and your marginal tax rate is 28.4%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of ₦100 in your salary will be taxed ₦28.37, hence, your net pay will only increase by ₦71.63.
A ₦1,000 bonus will generate an extra ₦716 of net incomes. A ₦5,000 bonus will generate an extra ₦3,582 of net incomes.