How much would IMF bank taxes raise?
If the UK implemented the duo of taxes proposed by the International Monetary Fund, the proceeds could be very substantial indeed.
My estimate, based on the parameters set out by the IMF, is that the take from financial firms from the two would be between £5bn and £10bn per annum.
That's based on what the IMF says should be a possible rate for any new tax on the profits and pay of financial institutions, and also what it indicates should be the yield from the separate liabilities tax for countries like the UK with relatively large financial sectors.
Such a sum would make a useful dent in the ballooning British deficit - although the IMF is (naturally enough) explicit that it doesn't think such taxes should be dedicated to filling a fiscal hole, but should be a provision to meet the costs of future financial crises.
What's striking is that proceeds of such magnitude massively exceeds what any of the main political parties currently say they want to raise from new bank taxes.
The Tories have said that their planned bank tax - which looks very similar to the IMF's Financial Stability Contribution, as a levy on what banks borrow - would raise around £1bn.
And the Lib Dem's tax on banks' profits - arguable a "lite" version of the IMF proposed Financial Activities Tax - is budgeted by Vince Cable to generate £2bn a year, rising to £3bn in 2014/15.
As for Labour, it has kept its powder dry, preferring to wait for what the IMF had to say (see last night's note for more on this).
That said, the government has already raised £2bn from its one-off tax on bonuses. And Alistair Darling has already in the past few hours made it clear that he believes that the IMF proposals give him licence to do a lot more.
Among those who'll be very disappointed with the IMF proposals are Adair Turner, chairman of the Financial Services Authority, and campaigners for a tax on financial transactions, or a Tobin Tax.
The IMF is explicit in rejecting Lord Turner's argument that a Tobin Tax could make a useful contribution in reducing the bloated size of financial markets or their volatility.
It does look, in spite of the passion of its proponents, as though the Tobin Tax is dead.