The Westminster government is to give the NI Executive an extra £1bn to support the Stormont deal.
A further £1bn will be added to Stormont's budget as an automatic result of spending plans for the entire UK.
The government said there will be "a rapid injection of £550m to put the executive's finances on a sustainable footing".
That will include £200m to resolve the nurses' pay dispute.
The government said the financial package will "be accompanied by stringent conditions" contained within the Stormont deal, around "accountability for public spending" and the development of "sustainable public services".
It added that the deal includes strict financial conditions, such as the establishment of an independent fiscal council.
However, the government added there are no stipulations for extra revenue-raising by the executive.
'Act of bad faith'
The Stormont parties are likely to be unhappy both about the size of the package and how it was announced.
On Wednesday night, Finance Minister Conor Murphy described the offer as an "act of bad faith", saying it "makes our job much more difficult".
"The bottom line is with this proposed package, our public services face a shortfall of at least £1bn next year alone," he said.
He said the the proposed package adds £100m to the £150m previously committed for legacy institutions.
"This falls at least £50m short of the projected cost of £300-£400m," he said.
The Sinn Féin MLA suggested that the announcement from Westminster was made "against the request" of the first and deputy first ministers. He hopes to meet the Chancellor next week for further talks.
The SDLP leader, Colum Eastwood, was equally unimpressed: "The gulf between the ambition of the deal and the money on the table is substantial and will cause serious public finance difficulties for the executive.
"This is not, and cannot be, the end of the matter," he said.
"I am, however, pleased to see earmarked and ring-fenced allocations for the expansion of Magee and a new addiction centre for the north west."
'Get on with it'
However, in a tweet on Wednesday night, Secretary of State Julian Smith defended the funding and urged politicians to "get on with it".
He posted: "Let's remember MLAs have been off work three years at a cost of [more than] £15m in salaries.
"There will be a new deal for NI as it leaves the EU. There is also a UK budget in spring. £2bn is biggest ever NI talks settlement and it addresses a number of key issues."
Earlier, he had said the money will "help transform public services in Northern Ireland, including ending the nurses' pay dispute".
Let’s remember MLAs have been off work 3yrs at a cost of £15m+ in salaries. There will be a new deal for NI as it leaves the EU. There is also a UK budget in spring. £2bn is biggest ever NI talks settlement & it addresses a number of key issues. Let’s get on with it...— Julian Smith MP (@JulianSmithUK) January 15, 2020
A new joint board formed between the government and executive will oversee how the money is spent.
The financial package includes:
- The £1bn investment as a result of UK spending plans, which will include funding for infrastructure investment
- The "rapid injection" of £550m to Stormont's budget, including £200m to end the nurses' pay dispute and deliver pay parity over the next two years
- £60M of ringfenced capital to deliver a medical school in Londonderry, subject to executive approval
- £50M over two years to support the rollout of low-emission public transport
- About £245m to support transformation of public services, with money being released depending on the delivery of reform
- £140m to address Northern Ireland's "unique circumstances"
It is not yet clear which spending commitments relate to the deal and which are the result of the automatic increases.