The government warns that the results of the ongoing negotiations on Brexit will not lead to major changes in trade with the EU, for which businesses should prepare.
The customs declarations are complex. They occupy as many as 208 pages of government guidelines for imports and exports, which will take effect after the end of the transition period at the end of this year.
It is very detailed and represents a complex checklist of firms that want to be prepared for the most significant changes in doing business with their largest and closest partner.
The government recommends that companies hire an intermediary, such as a customs agent or forwarder, to help them navigate the new requirements, or they can buy special software to access HMRC systems if they want to do it themselves.
Other requirements include filing an application for the registration and identification number of an economic operator, ensuring that carriers have rights to obtain a driver's license, and that their VAT accounting processes are ready for import into the EU.
Cabinet Minister Michael Gove said on Monday that the UK's departure from the EU "opens up many new opportunities for expanding trade with the rest of the world."
But the negotiations on a trade agreement with the United States encountered an obstacle in relation to food standards and animal welfare.
Relations with China, meanwhile, became tense in connection with the proposal to the British government to provide British citizenship for 3.5 million people in Hong Kong.
Such factors made many ministers admit that in the short term, the flow of business between the UK and the EU will be disrupted, but this price is worth paying for to be able to control their own borders, laws and money.
Thus, the tone of today's advice is clear, but many firms will check the compliance process. From the 200 pages of detailed instructions, it is also clear that any hope of less paperwork and red tape after Brexit is very unlikely.