Hefty Amount asked to be paid after Tax assessment.

Making a comparioson without knowing specific factors its hard to say something.

Those are :

Your yearly brut income

Your monthly tax deduction

Your other incomes etc..

But if FOD Financien saying so mostly they are accurate with calculation.

It is pretty normal. 463euros is pennies. I would not even consider it hefty. My in-laws had to pay a bit over 3500euros additional. This related to the employer not withholding enough on your monthly pay. In the end government will do the calculation and if you owe them like you do you have to pay. If they owe you then  you get a refund. So pretty normal here.

It is pretty normal. 463euros is pennies. I would not even consider it hefty. My in-laws had to pay a bit over 3500euros additional. This related to the employer not withholding enough on your monthly pay. In the end government will do the calculation and if you owe them like you do you have to pay. If they owe you then you get a refund. So pretty normal here.
-@Edigj

Thanks for your reply, I understand it now.

But does that mean I will not get the yearly tax refund  now? which with the "expact status" people like me were getting till last year?

Different, salary different benefits, different family situation, different communes, different sectors/parital comities etc etc. Do not compare, every situation is different. You will have to pay and there is no excess tax meaning no refund for 2022 tax year. What happens for 2023 tax year that depends on the above factors as well.