New WA: If no free trade deal can be reached (? ), then the UK will manage customs on behalf of the EU down the Irish Sea for certain goods.
Barnier:
“Northern Ireland will remain in the UK customs territory. It will therefore benefit from the UK future trade policy. But Northern Ireland will also remain an entry point into our single market. So what have we done to square this circle? UK authorities can apply UK tariffs on products coming from third countries as long as those goods entering Northern Ireland are not at risk of entering our single market. However, for goods at risk of entering the single market the UK authorities will apply the EU tariffs.”