Shadow Scottish Secretary Ian Murray immediately criticised the First Minister, as he argued the SNP are withholding the figures as they know “it’s likely to be bad news”.
The impact that leaving the UK would have on incomes is not the only thing the SNP is not providing an answer for, though.
In a recent report, political commentator and founder of the strategic analytics consultancy Diametrical Ltd. Andrew Willshire, claimed “citizenship” is another issue Ms Sturgeon’s party has not given much thought to.
Mr Willshire warned it could actually spark a crisis in both Scotland and the UK.
He explained: “Let us assume that independence day is upon us and that somehow Scotland has been able to negotiate acceding to the EU without a decade in the wilderness.
“The time has come to decide who gets Scottish (and therefore EU) citizenship as a matter of right.
“Who passes the test?”
The franchise for the independence referendum includes everyone legally resident in Scotland, regardless of nationality.
It should surely be assumed that all of those people would be granted Scottish citizenship, Mr Willshire noted, as if they weren’t, their votes could not be reasonably counted in the referendum.
He added: “Such an expansive offer of citizenship would certainly fit with the SNP’s view of Scotland, even if it doesn’t chime with the view of most Scots.
“Next, would Scottish nationals resident elsewhere in the UK (such as myself and 750,000 others) be entitled to Scottish citizenship?
“We are currently denied a vote on whether we want it to exist at all, but it would surely be hard to refuse it.
“But would it be automatically conferred or would we have to apply? What about spouses and children? And what of the many millions of British people who could claim Scottish citizenship based on recent ancestry? Even a conservative estimate would put that number at many millions.
“Scotland could be the first state where a majority of its citizens were not actually resident in the country, a bizarre state of affairs for a new country to find itself in.”
From the British side, the political commentator argued, it is also confusing.
He said: “It is not clear that the rest of the UK would permit dual citizenship as a matter of right — doubt has previously been cast on the matter (to the disdain, bewilderingly, of the SNP).
“Ireland provides some precedent, with all Irish citizens born before 1949 automatically being British subjects (which is why Terry Wogan could be knighted), but more recent examples, such as the dissolution of the Soviet Union, would require people to choose one or the other.”
Mr Willshire concluded: “Given the fundamental importance of such matters, it would be nice to think that the Scottish Government would have some clear answers or at least some clear aspirations.
“Unfortunately, it seems that citizenship is destined to join the currency, the border, the constitution, the EU, NATO, and every other item of consequence in the ‘too hard, wait till after the referendum’ bucket.
“Still, at least we know what the flag will be.”
London to be handed post-Brexit boost with Britcoin [EXCLUSIVE]
Alastair Campbell’s heartbreaking confession about Prince William [REVEALED]
Brexit deal torn apart by Labour Leaver as Hartlepool vote looms [INSIGHT]
In a recent interview with Express.co.uk, Alan Winters, director of the Trade Policy Observatory at the University of Sussex, argued there is something “very perverse” in wanting to end a 300-year-old Union in favour of the EU.
Mr Winters said: “It would be costly on both sides.
“More costly for the Scots for sure but it would also be a massive, massive political distraction.
“I also think the majority of people around the world would perceive this as English nationalism driving away the Scots, which is a rather unsympathetic view.”
According to Mr Winters, trade patterns would not necessarily change in case of independence, but “the amount of trade would go down and incomes would go down”.
When asked if a Scottish break-away would be more expensive than Brexit, Mr Winters added: “Absolutely.
“There is something very perverse in saying, ‘You dragged us out of a Union which has been going on for 50 years.
“Therefore we are going to pull out of a Union which has been going on for 300 years.”
Recent analysis by the London School of Economics’ (LSE) Centre for Economic Performance found Scotland’s trade with the rest of the UK is around four times larger than its EU trade.
The creation of a border between Scotland and the rest of the UK would increase costs by 15 percent in an “optimistic scenario” and 30 percent in a “pessimistic” one, according to the LSE.
The LSE estimated that the impact of independence, in addition to Brexit, would reduce Scottish incomes per capita by between 6.5 and 8.7 percent in the long term.
The LSE concluded that the trade benefits of rejoining the EU would not be enough to justify the cost of leaving the UK, “since the benefits of lowering trade barriers with the EU by rejoining are roughly offset by the costs of putting the EU’s external border between Scotland and the rest of the UK”.
The study noted that rejoining the bloc would be more beneficial than remaining in the UK “only if independence is sufficiently trade-destroying that the rest of the UK becomes a less important trade partner for Scotland than the EU”.