Wine Society describes planned alcohol duty changes as ‘ludicrous, expensive and probably unworkable’
Archived version: https://archive.ph/fTHRO
So
The government acknowledged the new administrative burden for businesses and put an 18-month “easement” period in place. During this period all wines between 11.5% and 14.5% would have to pay £2.67 in tax, the 12.5% ABV duty rate.
and
Analysis by the Wine and Spirits Trade Association (WSTA) has found that when easement ends prices on about 43% of wines will increase.
So, it must be going down or staying the same for 57%. Oh noes, what a calamity.
It is a bit more complicated to tax by % ABV rather than per bottle but it really is not that much more complicated. The retailers have all the data needed to do the calculation, it's not like they were previously working out their tax bill by hand-counting bottles of wine.
Both taxation systems are crap, of course. The per bottle and per 0.1%ABV schemes are so that they don't have to do it by price because taxing rich people would be wrong. Fuckers.