Hi Kayo,
We’re really sorry for the delay, we missed your first post by mistake, we don’t leave posts for such long without a response.
So your shop base country is NL, all customers have to pay VAT, registered companies in BE will buy without VAT, regular customers from BE will pay.
Here is what you need to do:
Plugin settings >> Validation & Progress tab >> make sure “Exempt VAT for valid numbers” is ticked, on Preserve VAT, select “Base country” assuming your base is NL, if not, select “Comma separated list” and enter NL in the field after it.
This way, you should be able to achieve the results you need, make sure you add the correct VAT tax for BE under WooCommerce settings >> Tax >> Rates.
Please let us know if you need any further help.
Omar