The UK now has two months to reply to the letters from Brussels demanding "swift remedial actions to restore compliance with the terms of the Protocol".
The European Commission on Friday launched four new infringement procedures against the UK over the implementation of the Northern Ireland Protocol.
The EU's executive accuses London of failing to comply with the applicable customs requirements, supervision requirements and risk controls on the movement of goods from Northern Ireland to Great Britain.
It also says the UK government has failed to implement EU rules on Value Added Tax (VAT) for e-commerce and failed to notify that they will implement EU rules related to indirect taxes, in particular on alcohol and alcoholic beverages.
In short, the UK is not providing the EU with export declarations Northern Ireland businesses are supposed to fill in when sending goods to Great Britain, including for controlled goods subject to prohibition and restrictions.
"This is of course very important to so that to ensure that the EU can comply with its own international obligations in relation to prohibitions and restrictions on the exports of goods to third countries. The UK, as of today, has not implemented these requirements," Commission spokesperson Ariana Podestà said.
The UK government, which described the new procedures as "disappointing", now has two months to reply to the letters from Brussels demanding "swift remedial actions to restore compliance with the terms of the Protocol".
If the reply is unsatisfactory, the Commission could then refer the matter to the European Court of Justice.
Draft bill vs infringement procedures
These four new infringement procedures add to the three already launched last month.
These were related to the UK's draft bill to unilaterally override parts of the international treaty, the continued lack of infrastructure and staffing to carry out customs checks in the UK, and London's failure to share trading data as required under the Protocol.
The British legislation unveiled last month and currently making its way through parliament would override parts of the agreement by creating so-called green and red channels to waive customs checks for goods travelling between Great Britain and Northern Ireland and are intended for the Northern Irish market only. It has been branded "illegal" by Brussels.
The Commission confirmed on Friday that they have not yet received a reply from the UK.
The Northern Ireland Protocol -- a key Brexit agreement that leaves Northern Ireland within the bloc's Single Market-- has been a source of continued strife between London and Brussels since the UK officially left the European Union on 1 January 2021.
The UK government, which negotiated and agreed to the protocol, now says it endangers the Good Friday Agreement it was made to protect and which ended decades of bloody sectarian violence in Ireland.
London demands that the whole treaty be renegotiated which Brussels has steadfastly rejected, calling for solutions to be found within its framework.
EU has 'bent over backwards'
Brussels' new infringement procedures come in the midst of a leadership contest in the UK to replace Prime Minister Boris Johnson who resigned two weeks ago after a mass walkout of ministers over his handling of several scandals into lockdown-breaking parties held at Downing Street and inappropriate behaviour by some of his MPs.
Only two people are now left in the running: former Chancellor Rishi Sunak and Foreign Minister Liz Truss who is also in charge of Brexit.
Eric Mamer, the Commission's Chief Spokesperson, stressed to reporters that the EU's executive "launches infringement when it considers that the conditions are met and when it is ready to do so."
He said that Brussels has "been extremely patient" and has "engaged with the United Kingdom over a very long period of time" to find solutions.
"We have bent over backwards in terms of making proposals to solve these issues. We are still in the situation where in fact the UK is not implementing its part of the deal in respect of many of the variables," he went on.
"If we thought that the prospects were great of sitting together on Monday and coming to a solution, we would not be launching the infringements, right? That's the logic."
A UK government spokesperson meanwhile said that they "will review the EU’s arguments and respond in due course."
"It is disappointing that the EU has chosen to bring forward further legal action, particularly on goods leaving Northern Ireland for Great Britain which self-evidently present no risk to the EU single market.
"A legal dispute is in nobody’s interest and will not fix the problems facing the people and businesses of Northern Ireland. The EU is left no worse off as a result of the proposals we have made in the Northern Ireland Protocol Bill," they added.