The government is set to launch a multi-million pound “Get Ready for Brexit” campaign on Monday, as businesses awaited details of the complex customs regime they will face. More information about the campaign, which will be partly aimed at Britons living in the EU, will be confirmed by Michael Gove in TV interviews scheduled for Sunday. The controversial Brexit border plans – which were criticised this week by the international trade secretary, Liz Truss – will be published on Monday along with fresh detail on post-Brexit immigration. A 90-page draft of the new border arrangements, “The Border with the European Union, Importing and Exporting Goods”, seen by the Guardian, lays bare the complicated new paperwork facing all businesses from 1 January, whether there is a deal or not. Sources say a later draft runs to more than 100 pages and will give businesses the first confirmed details of the scale of the challenge they face in less than six months’ time. The draft version features flow charts and “process maps” instructing businesses on the steps they will need to take in future and needs a three-page glossary to explain some terms relating to importing and exporting. It notes that from January, all businesses trading with the EU need to prepare for customs declarations, which have not been required since 1993, when the single market brought down trade barriers. A series of new inland customs clearance centres and border control posts are expected be built to alleviate congestion in ports including Dover, Portsmouth and Holyhead. New VAT and excise duty arrangements will also apply, with checks to confirm the ID of the driver and that the cargo matches the paperwork provided. Hauliers will be warned that if they bring in goods for personal use such as alcohol and cigarettes, they will have to be checked even if their cargo is cleared by customs. “When traders return to the UK, if they bring goods back in their baggage, they should go through the red channel at customs,” it says. Under a phased-in approach lasting six months, the government will hope to get tens of thousands of businesses familiar with the new system, but some fear the IT needed for the so-called “Goods Movement Vehicle Services” will not be ready in time. It will be trialled in Northern Ireland in November, according to an 11-page HM Revenue and Customs document seen by the Guardian. Last year, the government launched its first “Get ready for Brexit” campaign ahead of Britain’s planned departure on 31 October, urging businesses and individuals to prepare. It was halted three days before the UK was supposed to leave, as the EU granted another extension. It is believed that there will need to be a further campaign by the government if no trade deal is agreed with the EU. From 1 January an extra system would be in place involving tariffs on food, clothing and components in addition to the customs, VAT, security and health checks on animal and plant products. Checks will be phased in over six months, starting in January, a decision that led to conflict in the party, with Truss writing to Gove and the chancellor, Rishi Sunak, to warn that this could leave the UK “vulnerable” to smuggling and to a legal challenge by the World Trade Organization. While most of the communications will be aimed at businesses, the Foreign Office will also be launching a new advertising campaign on Monday to reach as many as possible of the estimated 1m Britons living in Europe to remind them of Brexit-related changes that will affect them. A government spokesperson said: “We are planning a comprehensive communication campaign from mid-July, to make sure people and businesses know what they need to prepare for the end of the transition period.”