Income taxes: when to pay extra?

Your income tax is levied at source (withholding tax, down payment). An adjustment to the tax payment is made the following year, following your spring tax return. With your 2021 income tax return for 2020, the tax administration will take stock of your tax situation and calculate the final amount of tax owed for your 2020 income.

When the tax calculated corresponds to the amounts already deducted at source, your tax is paid. You don't have to take any steps. If the calculated tax is higher than the total of the levies collected, you still have an additional tax to pay:

• up to €300 : in 1 time in September;
• more than €300 : in 4 times from September to December, around the 25th of each month for tax notices sent in summer 2021. In 2 times for tax notices sent in October 2021.

In addition to the tax top-up, you continue to be taxed at source for the current year.