[pjc50]

https://en.wikipedia.org/wiki/Ireland_v_Commission : it doesn't matter what the headline rate is, it matters what the effective rate is.

> "selective treatment allowed Apple to pay an effective corporate tax rate of 1 percent on its European profits in 2003 down to 0.005 percent in 2014."

Tricks include transfer pricing; company A charges company B an arbitrary number to reduce company B's profit to zero (so it pays no tax) but this gets classed as exempt in company A.