The Scottish Government has said a currency union makes sense for the UK as much as it does for an independent Scotland, after announcing a potential date for the move.
Scotland's Deputy First Minister Nicola Sturgeon revealed March 24th 2016 as the proposed date and previewed the country's "blueprint" for the future.
Ms Sturgeon said the 670-page document, which is due to be published on Tuesday, will "set out the social, economic and democratic for independence" and reveal "how Scotland will become independent".
ITV News' Scotland correspondent Debi Edwards reports:
However, Unionists say a currency union would not work for either Scotland or the UK. Scottish Secretary Alistair Carmichael said independence is about "political disintegration" rather than integration.
Speaking on BBC One's Andrew Marr Show, Mr Carmichael said:
Former chancellor and leader of the Better Together campaign Alistair Darling meanwhile raised the spectre of Scotland joining the euro.
Mr Darling said too that a currency union was looking like a "non-starter" and called for nationalists to explain their "plan B".
He told the Murnaghan programme on Sky News:
A Scottish Government spokeswoman said:
The independence referendum will take place on September 18 next year. March 24 is the anniversary of both the Union of the Crowns in 1603 and of the signing of the Acts of Union in 1707.