And it knows that the the total resources available for day to day departmental budgets will fall in real terms - down by 5% by 2020.
Finance Minister Arlene Foster has warned - again - of hard choices to come.
The first thing the executive needs to do now is strike a budget for 2016/17.
The timetable is tight - a budget paper will need to be produced before the end of the year and a draft budget released for consultation in January.
With a freshly minted agreement between Sinn Féin and the DUP, that process should be less than fraught than in recent years.
And with the chancellor's tax credits u-turn, the parties have one unexpected issue to grapple with.
Last week's 'Fresh Start' agreement set aside £240m to mitigate the impact of tax credit cuts - what does it get used for now?
The finance minister is not committed to using that money for other welfare mitigation.
She argues that "vulnerable people" can be protected by spending it in other areas like health and that the executive will need to discuss it further.
I would be amazed if Sinn Féin do not insist that the money stays in the welfare mitigation pot.
The parties also need to decide to what extent they want to follow in the chancellor's footsteps by continuing with protection for the health and education budgets.
They might also need to think again about their revenue raising powers.
Local councils in England will be allowed to increase council tax by up to 2% in order to fund adult social care.
That's a sector that is under major pressure due to tight budgets, rising demand and the impact of the National Living Wage.
Those pressures also apply in Northern Ireland - so could the executive consider its own "social care precept" by increasing the long-frozen regional rate?
The Northern Ireland Executive now knows how much money it will have to spend over the next few years.