Import container - is VAT always needed to be paid or only when container check?A

[tee]

Hi chaps, just wanted to run something by you guys.. I've been told by a friend that of 6 containers he only paid vat on 3, and these were the ones that got stopped and checked, I know this may not all be above board but is that possible? I was under the assumption that my forwarders have to pay vat in order to clear the container...? Can anyone shed some light on this, ta