dec 8, 2017 - UK signs Joint report and
agrees on NI backstop:
that in the absence of
any other solution,
Northern Ireland would
remain in “full alignment”
with the EU’s single market
and customs union rules
in all relevant sectors.
In exchnage EC agrees on transitional period until Dec 2020
and agrees to start future trade framework (trade deal) negotiations.
Future trade framework negotiations can finish only after the UK is 3rd country after 29 March 2019.
https://ec.europa.eu/commission/sites/beta-political