The government has finally conceded there will be extra checks and paperwork on some goods trade across the Irish Sea after Brexit. So why, on what, and when will they begin? Why will there be checks? They were agreed by Boris Johnson and the Irish taoiseach, Leo Varadkar, at a meeting in the Wirral last October. Although controversial and vehemently opposed by the Democratic Unionist party, they were cemented into law when they became part of the withdrawal agreement approved in January by parliament. They were proclaimed as the breakthrough to remove the need for checks on the border between Northern Ireland and the Republic of Ireland, which could have risked the continuing peace process. Didn’t Boris Johnson say there would be no checks? Yes. His statements during the election campaign confounded the EU and fuelled fears that the UK would try to wriggle out of the Northern Ireland protocol and push the border back to the land frontier with Ireland. What has changed? Reality has prevailed. The checks were legally agreed and, on Wednesday, Michael Gove confirmed them for the first time in a 23-page document. When will the checks be imposed? From 1 January next year, whether the UK strikes a trade deal with the EU or not. They will hold for at least six years under the withdrawal agreement. What will be the main checks? Checks on all live animals and on agrifood entering Northern Ireland from Great Britain will be conducted in airports and ports. This is to ensure the island of Ireland remains one epidemiological unit, minimising the prospect of disease being “imported” from Britain. Will there be any other checks? There should also be regulatory checks on the standards of goods. This is to ensure no sub-EU standard phones, TVs or toys, for instance, that could be permissible in the UK post-Brexit, enter the European single market (the Republic of Ireland) via Northern Ireland. The UK has said such checks will not be done at the border but in the market with spot checks in shops and warehouses, for example. What about tariffs? The government has said there will be no tariffs on goods entering the region from Britain but remaining in Northern Ireland. It has also said there will be no new customs posts or officials. This is a unilateral interpretation of the Northern Ireland protocol and remains to be discussed in detail with the EU. Anything else? Yes, the government has said there will be no exit or entry declaration forms. These are normally required for trade between EU and third countries and were identified as necessary by the former Brexit secretary Stephen Barclay shortly after the Wirral breakthrough summit. It remains to be seen if the EU will agree. How will it work in practice? Gove has said HMRC will be giving “extensive support” to businesses in the coming week and months and that dedicated teams are in place to work out the IT systems needed for the new VAT, excise and customs regime.