In 2021, the legal interest rate applicable in civil and commercial matters was still 1.75%.
In the attached document you will find a complete overview of the interest rates of the past years.
[1] Communication from the General Administration of the Treasury of the FPS Finance, Belgian Official Gazette of 1 March 2022, except art. 2, § 1 Law of 5 May 1865 on the loan against interest.