The IFS yesterday released its analysis of the effect of a minimum price for alcohol, and it made some interesting points.
Far from what one would believe from Theresa May's statement on the matter, and the press focus on "supermarket multi-buys" and "cut-price alcohol", it is by no means just the cheapest booze which would be hit by a proposed floor of 40p a unit. With the average price-per-unit just 44.8p in their sample, a total of 47.8 per cent of drinks would have their prices hit by the changes. For some types, it's even worse. Over 80 per cent of ciders will see price increases.
The correlations between price and wealth, and price and quantity consumed, are as you would expect (or even slightly weaker):
The average price for those with incomes below £10,000 per year is around 42p per unit, compared to 51p for those above £60,000. Households consuming fewer than 7 units of alcohol per adult per week pay almost 49p per unit, compared to 41p for those consuming more than 35 units.
One area where the report isn't quite so compelling, however, is in its call for minimum pricing to be enacted through the tax system rather than a simple floor.
In this, the authors echo an argument made by Matt Cavanagh in the Spectator last month (Cavanagh clearly being psychic, he managed to address the issues a month before the Home Secretary even raised them), when he wrote:
Last year’s IFS study  [pdf] estimated that, assuming ‘no behavioural response from consumers and no wider price effects’, the 45p MUP proposed by the SNP in 2010, if introduced across the UK, ‘would transfer £1.4 billion from alcohol consumers to producers and retailers’. By contrast, an MUP implemented indirectly, via changes in duty, would transfer this money to the Exchequer, which could reduce the need for spending cuts or tax increases elsewhere.
The problem for both the IFS and Cavanagh is that the single biggest argument the government has in favour of minimum pricing is wrecked if it is implemented through duty.
The rough plan (which would still be an enormous shake-up to the current way "sin taxes" are administered, and is likely illegal under EU law) would involve changing duty so that it is charged at a flat rate per unit, rather than the current variable rates depending on the type, as well as the strength, of alcohol. At present, only spirits, fortified wine and beer are taxed purely in relation to strength, with all other drinks merely striated into broad categories.
In order to prevent this increase being absorbed by supermarkets as a loss-leader (even with duty at the much lower current rates, it is possible to buy some drinks which are sold for less than the combined duty and VAT charged on them), this would have to be combined with legislation preventing shops from selling for less than the duty charged on the drink.
Enacting this plan would indeed result in a sharp rise in alcohol prices, with most or all of the increase going to the treasury rather than the supermarkets or drinks companies. But the increase would come from all drinks, rather than just the cheaper ones that the proposed minimum price is targeting.
With a minimum price, a drink which is already over the floor would see no price increase at all. If a three-unit bottle of beer costs at least £1.20 before the change, it will cost the same after. This allows the government to truthfully say that the price will hit heavy drinkers hardest and have the happy side-effect of aiding our flagging pubs (while slightly less truthfully claiming moderate drinkers aren't affected; the IFS confirms they are still "substantially affected").
The same is not true if the increase is put in through the tax system. That £1.20 bottle of beer may have around £0.60 of duty on it before the change, with production making up the other £0.60. After an increase, it suddenly has £1.20 of duty on it, with production still taking up £0.60. While, of course, supermarkets and drinks companies have profits which they may choose to cut into to prevent a price increase, it is unlikely they would be able to suck up all the extra cost.
In a 2011 paper , the IFS offer some concessions to this problem. They point out that as a percentage increase, a higher duty would still hit cheaper drinks more, and it is certainly the case that the public will be a lot more comfortable with any price rises going into general taxation than into the pockets of businesses.
Nonetheless, the strongest argument the government has in favour of minimum pricing is that it only affects the cheapest drinks and the heaviest drinkers. The IFS study already puts that on shaky ground, but trying to do the same thing through general taxation would blow a hole in the argument altogether. If the aim is simply to discourage drinking by raising prices across the board, then that can be achieved through taxation. But the aim of minimum pricing is more nuanced than that, and there's no point in pretending that it can be done any other way.