1 January 2021
The UK's post-Brexit transition period ends and the Northern Ireland Protocol takes effect, governing the movement of goods from Britain to Northern Ireland.
2 February 2021
The DUP under Arlene Foster sets out a five-point plan to achieve the removal of the protocol. It includes withdrawal from north-south meetings.
3 March 2021
The UK announces a unilateral extension of grace periods for supermarkets, leading to a legal challenge from the EU.
Around the same time, a group of unionists begin a legal challenge to the protocol, which will ultimately end up in the UK Supreme Court.
28 April 2021
Arlene Foster is deposed as leader of the DUP, to be replaced by Edwin Poots.
29 April 2021
The EU Parliament endorses the Trade and Co-operation Agreement, as the Brexit deal is formally known.
10 June 2021
It emerges that the US has issued a formal reprimand (a demarche) to the UK over its protocol position.
18 June 2021
Edwin Poots is ousted as DUP leader following internal party tension over a planned deal on the Irish language legislation.
He had only been elected on 14 May.
30 June 2021
Jeffrey Donaldson replaces Edwin Poots as DUP leader.
21 July 2021
The UK government publishes its Command Paper, setting out its aims for a renegotiated NI Protocol.
26 July 2021
The EU publishes proposals for protocol changes covering agri-food checks and medicines.
27 July 2021
The EU pauses legal action against UK over its unilateral extension of grace periods and publishes more examples of flexibilities it is prepared to consider over the movement of goods between Britain and Northern Ireland.
6 September 2021
The UK's then Brexit lead David Frost announces plans to extend all grace periods unilaterally.
9 September 2021
Maroš Šefčovič visits Northern Ireland to meet politicians and business leaders to take soundings on the operation of the protocol.
22 September 2021
Ahead of talks with then British prime minister Boris Johnson, US President Joe Biden says peace must not be jeopardised by the outworking of Brexit.
28 September 2021
The leaders of four unionist parties, DUP, UUP, TUV and PUP, issue a joint declaration of opposition to the protocol.
4 October 2021
David Frost tells the Tory Party conference that without changes to the protocol, the UK government is prepared to trigger Article 16, which is the dispute mechanism within the UK/EU Brexit deal.
11 October 2021
Belfast's High Court rules that the DUP decision to withdraw ministers from north-south meetings was in contravention of Stormont's ministerial code and a breach of legal obligations.
It does not make any order in respect of returning to them.
13 October 2021
The EU sets out detailed proposals to ease problems around the protocol, they include simplified certification for agri-food and a huge reduction in paperwork and new rules around certification of medicines.
31 October 2021
Maroš Šefčovič says he fears the UK is set on a path of confrontation.
3 November 2021
The then taoiseach Micheál Martin says triggering Article 16 would have a profound impact on future UK/EU relations.
18 December 2021
David Frost resigns as UK Brexit lead to be replaced by Liz Truss, the UK's foreign secretary.
Chris Heaton Harris, who'll go on to become Northern Secretary, is appointed her number two.
The following weeks will see repeated warnings by Ms Truss of her willingness to trigger Article 16.
24 January 2022
DUP leader Jeffrey Donaldson, who has been demanding movement by the UK government in recent weeks, says he will act soon if he does not see any.
3 February 2022
Jeffrey Donaldson withdraws DUP first minister Paul Givan from the Executive, effectively collapsing it.
The assembly continues to operate before ultimately being dissolved for a 5 May election.
This period sees a series of loyalist rallies called in opposition to the protocol.
5 May 2022
Stormont Assembly election sees Sinn Féin emerge as the biggest party, making Michelle O'Neill the next First Minister Designate.
DUP refuses to re-enter powersharing until its protocol concerns are addressed.
The following week it also refuses to support the election of an assembly speaker, effectively mothballing the devolved institutions.
10 May 2022
Liz Truss says the EU's October proposals are not enough.
Speculation grows about a UK plan to legislate to unilaterally change the protocol.
13 June 2022
As Boris Johnson's leadership comes under increasing pressure from within his own party, the UK government sets out plans for a NI Protocol Bill, which will give it the power to disapply large parts of the protocol.
It includes plans for red and green lanes for goods moving to Northern Ireland, creates a dual regulatory regime for manufacturers and a new dispute resolution mechanism that would replace the role of the European Court of Justice.
15 June 2022
EU reacts badly to the proposal, restarting earlier paused legal action against the UK and promising new ones. It also fleshes out in greater detail some of the flexibilities it is offering.
7 July 2022
Boris Johnson resigns as British prime minister after a series of scandals.
There have been no formal EU/UK talks since February and everything is now put on hold pending the election of a new leader.
5 September 2022
Liz Truss takes over as prime minister, defeating Rishi Sunak in the leadership election.
She appoints arch Brexiteer Chris Heaton-Harris as Northern Secretary and James Cleverly as Foreign Secretary and Brexit lead negotiator.
20 October 2022
Liz Truss resigns as UK prime minister after a disastrous, uncosted, tax-cutting mini-budget, which spooks the markets.
Rishi Sunak takes over five days later.
26 October 2022
In telephone talks with European Commission president Ursula von der Leyen, Mr Sunak reiterates his preference for a negotiated settlement to the protocol issues.
28 October 2022
A deadline for a fresh assembly election passes. Having talked tough on his determination to call one, Chris Heaton-Harris postpones it.
He will later push the deadline out to 2024 to allow time for UK/EU negotiations to bear fruit.
11 December 2022
DUP leader Jeffrey Donaldson writes to the Northern Secretary to complain about the "tediously slow" progress of the NI Protocol Bill.
It is clear it has effectively been paused by the UK government, presumably as a confidence-building measure with the EU in the talks, but also because the House of Lords is promising to rebel over it.
18 December 2022
Leo Varadkar replaces Micheál Martin as Taoiseach.
Mr Martin takes on the Minister for Foreign Affairs role.
19 December 2022
The EU announces a three-year extension to grace periods on veterinary medicines from Britain to Northern Ireland. An impending cliff edge had been causing real concern to the north's agri-food industry.
9 January 2023
The EU/UK announce a deal on real-time data sharing about goods travelling from Britain to Northern Ireland.
It would allow the EU to take a risk-based approach to checks and is heralded as a sign of major progress and a harbinger of a wider protocol deal.
11 January 2023
UK Foreign Secretary James Cleverly in Belfast for talks with the parties.
It turns to farce when Sinn Féin leader Mary Lou McDonald is excluded.
12 January 2023
Taoiseach and Tánaiste arrive in Belfast on the same day for talks with parties and the Northern Secretary.
Mr Varadkar concedes mistakes were made in the introduction of the protocol and says he wants to rebuild relationships with the UK and unionists.
31 January 2023
The Times Newspaper reports a deal is close, that the EU has accepted a red land/green lane approach to goods and made concessions on the role of the European Court.
6 February 2023
RTÉ quotes senior EU sources saying they will accept the red lane/green lane approach and that it will apply to agri-food checks, as well as customs declarations.
The role of the ECJ is said still to be causing difficulty.
8 February 2023
The UK Supreme Court rules the NI protocol is lawful in response to a challenge from unionists.
The politicians say the court case has exposed their concerns about its economic and constitutional impact.
11 February 2023
BBC reports that the EU/UK talks are in their end stages.
15 February 2023
Daily Telegraph says a deal likely to be unveiled in a fortnight.
17 February 2023
British Prime Minister Rishi Sunak arrives unexpectedly for talks with the parties in Belfast.
At the same time, James Cleverley meets Maroš Šefčovič in Brussels.
Mr Sefcovic says progress has been good and joint solutions are the joint objective.
There is speculation that the deal may be announced in days.
19 February 2023
Former British prime minister Boris Johnson intervenes in the issue, warning his successor not to drop legislation that would allow the UK to override the protocol.
A number of British media reports said Mr Johnson was attempting to scupper the proposed deal.
Media reports also claimed Mr Sunak could face a potential rebellion from hardline Brexiters within his party if any deal allows the European Court of Justice to retain jurisdiction in Northern Ireland.
Elsewhere, Tánaiste Micheál Martin is in Brussels meeting EU Chief Brexit negotiator Maroš Šefčovič, as the diplomatic push to get a deal between the EU and UK on the Northern Ireland Protocol continues.
Micheál Martin met the British Prime Minister Rishi Sunak at the Munich Security Conference over the weekend. He also held discussions with UK Foreign Secretary James Cleverly.
20 February 2023
British Prime Minister Rishi Sunak is expected to brief his cabinet early this week on the state of play in negotiations between the UK and EU on the Northern Ireland Protocol as speculation continues that a deal could be imminent.
He will seek to convince a majority within his own party to back any forthcoming agreement.
