Permanent secretaries in charge of the UK's devolved governments have told MPs of crunch points they face in their relationship with Whitehall.
Their comments came at a session of parliament's Public Administration and Consitutional Affairs Committe, which is probing central government's devolution capability.
Jayne Brady, who is head of the Northern Ireland Civil Service, told Tuesday's session there was "still a lack of awareness" of the way constitutional arrangements in Northern Ireland differ from England, Wales and Scotland.
Brady said the lack of understanding in policy terms had initial impacts for the distribution of funding to replace the European Structural and Investment Programme (ESIP) in the wake of the UK's departure from the European Union and also some categories of levelling up funding.
She told PACAC that the Shared Prosperity Fund – created as a successor to ESIP – and levelling up funding streams had been based on GB government structures, where more functions are fulfilled at local-authority level.
"Housing is entirely within an arm's length body of one of our departments and there isn't a devolved housing authority," she said.
"We have, within our Department for Infrastructure, control of our transport, our rail, our bus network, and indeed our water systems. So in terms of bidding for some of those projects as part of levelling up and Shared Prosperity they were not initially open for departments to bid into – even though that was the broader intent, as I understand it."
Brady said the policies had been "architected with a basis of a different structure".
Scottish Government permanent secretary John-Paul Marks told MPs Brexit had created a "different operating environment to devolution", compared with what went before.
He cited the Sewell Convention, under which the UK government agrees not to legislate without consent from devolved governments.
"Up to 2018, there were no circumstances where that consent was not granted," he said. "Since 2018, there's been 11 occasions where that convention has not been followed.
"To an extent, that reflects a changing nature of the political context post-Brexit and given the UK Internal Market Act."
Marks said improvement would require early engagement with the UK government and an operating environment in which common frameworks were made to work "really well".
Elsewhere in the session, Brady was asked about views expressed by former Cabinet Office minister Sir David Liddington, who argued at a previous hearing that NICS should lose its separate status from the Home Civil Service.
Liddington argued that it would be better for secondments and other cross-learning oppportunities if civil servants working for the devolved administration in Northern Ireland did so on the same basis as counterparts in Scotland and Wales.
Brady declined to offer an opinion.
"Any discussion of the constitutional arrangments for Northern Ireland would be for those who are elected to make that decision," she said.