It counts. Not as zero — that is exactly the point of the Belgian method.
Under the globalisation method, as Belgium applies it, a loss on one piece reduces the profit made on your other pieces in that same return period. So you count it in. If you work per piece, as the French default rule does, a loss counts as zero and reduces nothing.
A bad buy is therefore less costly than it looks. Sell a cabinet at 200 euros profit and a mirror at 80 euros loss in the same quarter and your taxable margin is 120 euros, not 200.
The condition is that you can show the purchase price of both pieces. A loss you cannot prove does not exist for the return — and then you pay on the full profit of the others after all.
Sources, each checked on 31 August 2026: Royal Decree no. 53 of 23 December 1994 (Belgium), Belastingdienst (Netherlands), article 297 A-II of the CGI and BOI-TVA-SECT-90-20 on bofip.impots.gouv.fr (France), and gov.uk (UK).
This is an explanation, not tax or legal advice. Put your own situation to your accountant.
In Belgium the profit margin is looked at per return period: you add up all purchases and all sales in the period and only then take the difference. That is the globalisation method. In France the statutory default is per piece, with globalisation as an option; in the UK the Margin Scheme is per piece and Global Accounting per period.
Then no margin VAT is due for that period, and you get nothing back: a negative margin does not create a credit. The shortfall may usually be carried forward to the next period, where it lowers your margin there. Discuss the carry-over with your accountant — for the Netherlands the Belastingdienst puts it in exactly those words.
Vintro Pro keeps, per piece, what you paid, when, and where it came from. Your stock list and your margin VAT build themselves while you work.
Free up to 10 pieces, no card number and no end date.