When posting workers to another EU country employers should beware of failures on behalf of the social security authority in the posting country, as this will allow the host country authorities to declare that E101 social security certificates are fraudulent and disregard them. In a case before the ECJ, Bulgarian companies had posted workers to work on a Belgian construction site. Belgian authorities are invariably suspicious of workers posted from Eastern Europe and made enquiries with the Bulgarian social security authority – that failed to respond. The court also judged, perhaps wrongly, that the posting companies were just “paper entities”. The Belgian Company and its top executives, were therefore found guilty of fraud and other charges relating to the posting, even though they simply relied on documents they believed to be genuine. This is especially of concern as it would appear that there was no evidence whatsoever that the E101 certificates were forged (Case C-359/16).