[alexkus]

You don't have to move offices to start doing the road of tax avoidance. It's all about where you channel your money internally if you have two companies operating in different tax regimes.

It'll be interesting to see what they do with the profits from their companies (both the US and Ireland).

If they keep a chunk of income in Ireland and only transfer it to the US during tax amnesties then that's one standard form of avoidance.

If the US Dropbox entity starts paying a large sum of to Dropbox Ireland in order to license some part of the technology then we're in to the cunning world of tax avoidance proper.