A final decision on giving Stormont the power to lower corporation tax in a bid to boost inward investment could come within weeks.
First Minister Peter Robinson and Deputy First Minister Martin McGuinness are to have a further meeting on the issue with Prime Minister David Cameron in London as the long running controversy approaches crunch-point.
On a one-day visit to Northern Ireland, however, Mr Cameron emphasised that many complex issues still remain.
The comments came after the Stormont Executive handed over a report on the issue to Mr Cameron, who said he wanted to study it carefully.
Speaking after a meeting at Stormont Castle with the First Minister and Deputy First Ministers and the Secretary of State Theresa Villiers, Mr Cameron claimed progress was being made.
“I've always seen some major reasons and advantages for moving ahead on this, not least because of the land border you have with the Republic,” he said.
Earlier Mr Cameron had addressed workers at forklift truck manufacturer Nacco Materials Handling on the outskirts of Portadown, where he held one of his informal town hall-style meetings, in which he takes questions from the public.
His first questioner caused laughter when he expressed his disappointment that Mr Cameron had not chosen Lurgan as the location for the G8 summit.
If the Prime Minister decides to lower corporation tax, at a stroke it would make Northern Ireland better able to compete with the Irish Republic, where the rate is 12.5%. At present the main rate here, as with the rest of the UK, is 24%.
“Martin and Peter and I will be holding a further meeting on this issue in London,” Mr Cameron said. “There are a lot of complicated issues to be hammered out. It's not straightforward.”
Mr Robinson has indicated he expects a verdict before the end of the year.
Among the issues still to be agreed are the precise size of the corresponding cut in Northern Ireland’s block grant — with some estimates put at £700m — and what would happen to extra tax receipts that could be generated.