The U.K. government's argument that an independent Scotland would be too expensive to run has "zero credibility," according to one of the economists cited by the government.
In an effort to stem rising support for a Yes vote in September's referendum on whether it should quit the U.K., the government has released a statement claiming the bill for setting up new government departments could reach £2.7 billion ($4.5 billion).
Patrick Dunleavy, politics professor at the London School of Economics, whose work has been cited by the government in its forecasts, told CNBC his work had been "radically overstated" and the government's claims had "zero credibility."
The Treasury estimates suggest Scotland would have a size of government similar to the (much larger) UK, whereas it's fairer to compare Scotland with Denmark, Sweden or Ireland in terms of size of government, according to Dunleavy.
As it stands, the vast majority of opinion polls this year suggest a resounding Scottish vote to stay in the U.K.. However, some show the gap between Yes and No voters narrowing -- as well as a sizable number of people still undecided on which way to vote -- making it key for both sides to continue battling.
Further strengthening the No camp is a raft of businesses from banks to oil companies which have pledged to leave Scotland if it becomes independent. There have been increased concerns about just how to detangle Scotland's economy, heavily dependent on oil revenues and banks, from the rest of the U.K.
"The possibility of a UK breakup has generated political uncertainty within the country and confusion abroad," as Citi analysts have warned.
Danny Alexander, chief secretary to the Treasury, said: "The Scottish government is trying to leave the UK but it won't tell anyone how much the set up surcharge is for an independent Scotland.
"As part of the UK, Scotland gains from a strong and stable tax and benefits system."
Critics of the Scottish independence movement claim that its leaders have not set out a clear vision for its economic future, on issues like currency, central banking and European Union (EU) membership.
The movement wants to keep the pound and stay part of the EU, but both might be troublesome. If Scotland votes to become independent, it has been warned by EU authorities that it would not be able to apply for membership until 2016.
There may also be issues for a newly independent Scotland keeping both currency union and the Bank of England as its central bank.
"Even if a currency union was accepted, it still needs to go to a referendum for the rest of the U.K. We wouldn't sign up to the euro, so why would we sign up to another currency union? I think it might be difficult to win," George Buckley, chief UK economist at Deutsche Bank, told CNBC.
Yet ultimately, Scotland may also be aided by its geographic and economic intertwining with the U.K., as politicians from the rest of the island are aware that their economic success is linked to Scotland's.
"The last thing the rest of the UK wants to do is produce an independent Scotland which is not financially viable," Buckley pointed out.