George Osborne's stated justification  for abolishing the 50p income tax rate was that, due to mass avoidance, it raised "just a third of the £3bn" expected. Even by Osborne's standards, this was a peculiarly unconvincing argument. It's true that £16bn of income was shifted into the previous tax year - when the rate was still 40p - but this was a trick the rich could only have played once. Moreover, as the government has acknowledged in other instances, tax avoidance isn't an argument for cutting tax, it's an argument for limiting avoidance.
But leave this aside. The fact remains that, as Osborne conceded, the 50p rate raised £1bn (and had the potential to raise far more). Not a transformative amount, to be sure (the deficit is forecast to be £120.9bn this year), but hardly to be sniffed at. Indeed, it's precisely this argument that the government makes when justifying "tough" measures such as the "bedroom tax" (which it is hoped will save £465m a year): every little helps.
Osborne claims that the reduction in the top rate to 45p will cost the government just £100m but, once again, this is based on an anomalous year's data. Having brought forward their income in order to avoid the 50p rate in its first year, the rich have now delayed it in order to benefit from the reduction to 45p (again, a trick they can only play once) this year. The reality is that the cost of scrapping the rate is likely to be far higher, with up to £3bn in revenue forsaken. But as I show below, even if we accept the anomalous figure of £1bn, a significant number of the welfare cuts introduced by the government could have been avoided if the 50p rate had remained in place.
The "bedroom tax"
The measure, which will see housing benefit cut by 14 per cent for those social housing tenants deemed to have one spare room and by 25 per cent for those with two or more, is forecast to save £480m - less than half of the yield from the 50p rate.
It will cost 660,000 tenants an average of £14 a week or £728 a year. Exemptions have been introduced for 5,000 foster carers, some armed forces families and families with severely disabled children - but not families with a severely disabled adult .
Estimated saving: £465m a year.
Council tax support cut by 10 per cent
The retention of the 50p rate could also have paid for the reversal of the 10 per cent cut in council tax support, which is forecast to save up to £480m a year. The measure will cost 1.9 million families who do not currently pay council tax an average of £140 a year. In addition, 150,000 low income families will pay on average £300 more a year.
I've written about the policy in greater detail here  (Will this be the coalition's poll tax moment?).
Estimated saving: £480m a year.
Legal aid cuts
Alternatively, the 50p rate could have prevented the lowering of the cut-off point for legal aid to a household income of £32,000 and the introduction of a means-test for those earning between £14,000 and £32,000.
Estimated saving: £350m.
1% cap on benefit increases
Around half of the revenue raised by the 50p rate in its first year could have allowed the government to uprate benefits in line with inflation (which stood at 2.2 per cent in September 2012, the month traditionally used to calculate benefit increases), rather than by just 1 per cent.
Estimated saving: £505m in 2013-14.