The boss of one of the UK's largest customs brokers is warning of a 500% rise in customs processing if there is no deal to leave the European Union.
George Baker told BBC 5 live's Wake Up To Money he expects a no-deal Brexit to increase their workload by 500%.
He said it will be "very difficult to cope" if there is no Brexit deal.
Government papers released on Thursday warned importers and exporters to "begin taking steps to mitigate against" a no-deal exit.
A customs broker submits electronic declarations on behalf of import and export traders.
George Baker, whose business is based in Felixstowe, Suffolk, said, "There are many businesses which hadn't considered they may need a customs broker.
"They may have thought the import and export declarations are just a simple thing they can do and don't have much idea about how complex the transactions would be.
"It takes between two to five years to train to be a customs broker."
Brexit Secretary Dominic Raab said on Thursday that reaching a deal with the EU was the "overriding priority" and "by far the most likely outcome" but that "we must be ready to consider the alternative".
Allie Renison, head of Europe and trade policy at the Institute of Directors, said: "A lot of these companies don't know all the different information they need to put into this.
"You have a whole different raft of paperwork you don't currently have to deal with if you're an exporter to Europe."