Corporation tax: decision by summer
It could be the summer before Westminster responds on proposals to cut corporation tax, Peter Robinson said.
The Scottish administration also wants the power to set its own levy and has used Northern Ireland's discussions to help stake its claim, the DUP leader added.
A ministerial working group from London and Belfast is examining the region's case for a reduction to promote inward investment.
The First Minister said: "I suspect that on the present timetable we are more likely to be talking about a response from the Government in the summer than any time before that."
He said Scotland's future was not discussed at last week's British-Irish Council meeting. "It is a matter entirely for the people of Scotland as to what they should determine their future to be, but I very much hope that it will be as an integral part of the UK," he told the Assembly.
"There is an irony that at the moment, when there seems a real possibility of some form of break-up of the UK, that Northern Ireland is not the cause of it."