Brian and Julia McVey don’t think of themselves as particularly wealthy but Alex Salmond does. The couple, who live in the middle- class suburb of Lenzie, in East Dunbartonshire, earn about £100,000 a year between them but they still wince every April when their council-tax bill drops onto their doormat.

The current levy on their three-bedroom, semi-detached home is £1,649 a year, but the first minister doesn’t think this is enough. Under his plans for a local income tax (LIT) the couple, both in their fifties, would pay £2,970, almost double.

His pledge to replace the council tax was contained in the Scottish National Party’s manifesto at last year’s Scottish election but, given the level of opposition ranged against it, few believed he would actually go through with it. However this week, with characteristic brio, Salmond unveiled his detailed plans. The new tax is local only in name. It will be set centrally at 3p in the pound and collected by HM Revenue & Customs.

The first minister believes his scheme will be fairer than the hugely unpopular council tax. It will be directly linked to ability to pay and he claims it will lift 85,000 people out of poverty.

As Julia and Brian McVey testify, however, the burden will fall on moderate-earning, dual-income households, and their opposition is growing. A YouGov poll commissioned by The Sunday Times reveals that only 46% of voters favour the new tax.

Despite an end to council tax on his two houses in Bearsden and Rhu, businessman Stan Prosser will be about £3,500 a year worse off. “I won’t be voting SNP. This is going to hit those with higher salaries very hard and isn’t good news,” he said.

Even those who will benefit are not in favour. Agnieszka Bulow, a 34-year-old photographer from Renfrew, currently earns £30,000. Under the proposed local income tax she calculates that she will be £430 a year better off, but she sees it as a tax on aspiration. “The politicians do what is best for them. Maybe this legislation will be okay now, but in the future it could be bad for me,” she said.

As Margaret Thatcher found to her cost, the introduction of a new tax can bring a swift end to even the most feted political career. Her replacement of rates with the community charge, or poll tax, in the late 1980s led to rioting on the streets and to a cabinet revolt. Salmond knows all this, but so far hasn’t blinked, dismissing his growing ranks of critics as out-of-touch with the political mood of the country.

According to the Scottish government’s own consultation paper, some 67% of households overall will pay less, 15% see no difference, and 18% pay more. The figures for dual-income households and families, however, are markedly different. Ministers admit that almost a third, 30%, of “households comprising multiple taxpayers” will pay more. The highest-earning 10% of households will be on average £785 a year worse off.

In order for Salmond’s sums to add up, however, he needs the UK Treasury to continue sending £400m north each year in council tax benefit, even though the tax would not exist here. Unsurprisingly, the Treasury has rejected the idea out of hand, arguing that if council tax goes, so does the associated benefit.

Some MSPs suspect Salmond privately wants the Treasury to stand firm so that he can blame Labour in Westminster for denying Scots his marvellous LIT.

For Salmond to pass a bill on the local income tax, he would need the support of the Scottish Liberal Democrats, the Greens and possibly Margo MacDonald, the independent, to counter Labour and the Tories. But the Greens are opposed to the scheme and want a tax based on land values instead. The Lib Dems meanwhile want a different kind of local income tax where the rate is set by each council rather than by central government.

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