HMRC say that approximately 2% of all export declarations are not finalised on their system, and is carrying out an investigation as to why this should be the case. Investigations so far suggest that all parties; freight forwarders, shipping lines, air carriers, port operators and airline handling agents are all making mistakes. HMRC acknowledges that the export declaration procedure is relatively complex, as more than one party is likely to be involved in one of the three required stages. It is recommended that when freight and documents are passed along the supply chain, the next party should be advised that an export customs declaration has been created and that they must arrange the next step.