Belgium Corporate Income Tax (CIT)
In Belgium, the standard corporate income tax (CIT) rate is 25%; a small company can apply a reduced rate of 20% to the first EUR 100,000 of profit if it meets further conditions. Tax returns must be filed by September 30 for financial years ending between December 31 and February 28 of the tax year. For other cases, the deadline for filing is the last day of the seventh month following the end of the financial year. Extensions may be granted under certain circumstances, such as serious reasons or force majeure. The final payment is typically due within two months after receiving the assessment notice, and companies may choose to pay estimated taxes through quarterly installments.
PwC World Tax Summary

