If you transport, store or deal in plastic packaging (including packaged goods) that should have been subject to plastic packaging tax, then you could be required by HMRC to pay any unpaid plastic packaging tax that someone else in the supply chain should have paid.
The best protection from joint and several liability and secondary liability is to have good supply chain due diligence in place.
If you receive a joint and several liability notice from HMRC, it will specify the supplier it relates to. You should make additional checks with that supplier immediately and stop doing business with them if you are not satisfied that they are properly meeting their plastic packaging tax obligations.