British Prime Minister David Cameron is expected to sign a deal Monday with Scottish First Minister Alex Salmond that would allow Scotland to hold a referendum on independence sometime in late 2014, dpa reported.
The two are to meet in the Scottish capital Edinburgh.
With opinion polls giving a growing minority of Scots in favour of breaking away from England and Wales, the deal will fire the starting pistol on what is likely to be a heated campaign.
Scotland was given a devolved parliament, with limited powers, under the previous British government in 1999.
Scottish deputy first minister, Nicola Sturgeon, of the ruling Scottish National Party, said Sunday: "The good thing about getting the process issues out of the way, which we'll do tomorrow, is that we can get on to that substantive debate about why Scotland would be better as an independent country."
The ballot, which only those resident in Scotland will be able to vote in, is likely to be limited to a single Yes-No option.
Suggestions of a second question on further devolution, short of independence, were opposed by the British government in London.
In one innovation, the voting age is likely to be lowered to allow 16- and 17-year-olds to take part in the referendum.
The Conservative-Liberal Democrat coalition government in London is opposed to Scottish independence, as is the opposition Labour party.
Most opinion polls give the independence campaign about 30 per cent support, among the 4-million strong Scottish electorate.