Timeline: a collapse four years in the making
November 2012: An initiative to reduce carbon emissions called the Renewable Heating Incentive is announced by the then Enterprise Minister Arlene Foster. It financially supports businesses, public sector and other non-domestic organisations to meet the cost of more environmentally friendly technologies. Eligible applicants are told they will be entitled to help for 20 years.
Autumn 2013: A whistleblower contacts Mrs Foster and asks for a meeting to raise concerns over green energy. A second message is sent a few days later with more specific concerns about the RHI. At a later meeting with officials, her concerns are not taken seriously.
Autumn 2014: The RHI initiative is extended to the domestic sector by Mrs Foster.
January 2015: A formal re-approval of the scheme due from the Department of Finance is overlooked as a result of a "combination of staff changes and an administrative oversight". Meanwhile, applications for the initiative increase.
February: It is claimed RHI will over spend by at least £460m over a 20-year period. Mrs Foster's successor as Enterprise Minister, Jonathan Bell, announces his intention to close the scheme to new applications. An internal investigation gets under way.
July: In a damning report, the Audit Office says "serious systemic failings" in the scheme will cost the Northern Ireland budget hundreds of millions of pounds. It reveals a farmer will make £1m of government money just for heating an empty shed.
Its report concludes that the lack of a cap on subsidy payments meant that the more heat applicants generated, the greater the subsidy they were paid.
October: Stormont's Public Accounts Committee calls the mishandling of the RHI scheme "one of the biggest scandals" since devolution.
November: With the realisation that the funding available for applicants is uncapped, Stormont tightens the rules. But a massive late surge of 900 applications is received before changes can be made. The Public Accounts Committee is told that a £405m hole in the budget will have to be plugged over RHI's 20-year lifetime.
December 15: In an extraordinary TV interview, Jonathan Bell claims advisers attempted to remove Arlene Foster's name from documents linked to RHI, and that two senior special advisers "were not allowing this scheme to be closed" as costs began to spiral out of control. Mrs Foster responds by saying that if papers were altered "it wasn't on my say-so", and DUP special advisers Timothy Johnston and Andrew Crawford say they never sought to keep the RHI scheme open against the wishes of the minister.
December 16: Deputy First Minister Martin McGuinness calls for the DUP leader to stand aside as First Minister.
December 19: Arlene Foster faces a motion of no confidence as the Assembly is recalled for a special sitting to discuss the growing political crisis. The First Minister apologises for failing to put in place cost controls, but defends her role. The motion of no confidence fails on a cross-community vote. Arlene Foster addresses a virtually empty chamber after Stormont was recalled over the RHI scheme
January 9, 2017: Martin McGuinness announces his resignation as Deputy First Minister in protest at Mrs Foster's refusal to step aside during an investigation into the RHI.