Every time I see people, including Irish commentators, politicians and Ministers, talking about the quantum of the Apple case, I want to tear my hair out, here's why 1/n

There are three distinct issues here. The first is whether Appple paid insufficient tax to Ireland over the ten years at issue. The second is that if they did, how much did they do so by? The third is whether some of that tax is due to other States and not to Ireland 2/n

Dealing with 1 & 2 together Apple and Ireland are insisiting that Irish tax law was applied properly so no extra tax is due. Given this forms part of the original agreement between Apple and Revenue (we picked a number out of thin air) this position is simply not sustainable 3/n

However, the quantum of the aid is the amount of tax which ought to have been payable under Irish tax law applicable at the time, and the Commission decision on the aid does not appear to address this properly, it rather invokes an "interesting" approach to international tax 4/n

norms. The General Court or ultimately the Court of Justice might agree with the Commission's decision here, there is a slim precedent, and numerous other State aid cases are currently progressing where the Commission is using the same argument 5/n

But my view is that the GC should determine that the Commission is correct that there is an aid, but wrong in its methodologies for calculating that aid, and so should make them revisit their calculations 6/n

Given the amounts at stake and novelty of the case, an appeal to the Court of Justice is all but guaranteed, and I would assume it will later return to the General Court at least once 7/n

So issue 1 is to my mind clear, but issue 2 is unclear. How much was Irish tax underpaid by over the ten years subject to the Commission decision that there was an illegal State aid. Which brings us on to issue 3. How much of this aid claw back can Ireland keep? 7/n

The logic of the Commission here is that some of the profits which Apple should have booked in Ireland, should also have been booked in e.g. Germany and German tax paid on those profits. That German tax would then be creditable against the Irish tax, reducing the 8/n

amount of tax which Ireland would have to collect on those profits. However (subject to potential further State aid cases elsewhere) that requires e.g. Germany to assess Apple to back taxes _and_ for relief to be available against Irish tax for those back taxes 9/n

However, while we have seen Italy (€318m), France (€500m) and the UK (£137m) reach settlements with Apple in respect of back taxes (and potentially interest and penalties) we do not and cannot know how much of that is creditable against Irish tax 10/n

if any at all. This is complicated stuff, and draws on domestic tax laws (including domestic time limits for tax assessments/ claims) in multiple countries, along with EU State aid law (with potentially different time limits) 11/n

So for anyone to assert with confidence that they know what the answer to issue 2 is with any confidence beggars my belief, to assert you know the answer to issue 3 (without issue 2 first being determined) is staggering 12/n

If the European Courts ultimately conclude that the Commission is correct on quantum in relation to issue 2, and given Apple have settled with three of the largest EU Fiscs for €1bn plus change, then even if that is all tax which is creditable in Ireland 13/n

Ireland will ultimately retain most of the State aid. However, if, after significant litigation, the European Courts ultimately determine that the quantum of the aid is €2bn, and if Germany and other Fiscs raise assessments on Apple with such tax being creditable in Ireland 14/n

It is possible Ireland could retain none of the aid. So my plea is can everyone stop speaking with authority as to what the numbers are here? There is a whole lot of uncertainty, huge numbers, and potential for litigation in multiple forums, over many years, to resolve it. TY

And the decision today is that the Commission failed to prove that there was an aid, because by seeking to assert the full €13bn was taxable (which was always a reach) they failed to evidence that any Irish tax was underpaid. Had they been less ambitious they might have won.