Auction costs for the self-employed and VAT to be charged

The seller’s commission for traders is 6% (excl. VAT) of the allocated lot.
There is an exemption from VAT for small companies:

By intra-Community acquisitions is meant the introduction into Belgium of a good that is sent from a country that is a member state of the EU. If the Belgian purchaser has a valid VAT identification number, the purchase will be taxed in Belgium. The invoice must not state VAT. If the Belgian buyer is a taxable person who has to submit a periodic return, he will state the transaction and the tax in his VAT return: this tax is deductible.

If you are a trader located outside the EU, you don’t have to charge VAT either, because this transaction falls outside of VAT.