My point is that almost all of Apple's profit is in reality generated in California, even if its sales and accounting profits are booked overseas. So I'm compa

My point is that almost all of Apple's profit is in reality generated in California, even if its sales and accounting profits are booked overseas. So I'm comparing US-based profit with the US Federal tax rate. Let's say an iPhone is sold in the UK, generating a $200 profit. How much of that profit was really generated in the UK and how much in the US? The answer is to consider what would happen if Apple's US and UK operations were two distinct, independent companies: Apple in California would determine almost everything about the way iPhones are sold in the UK - where the Apple stores are located, what the stores look like, what their TV and billboard advertising should look like, what happens when a customer returns a product, etc. Apple US would then take this list of requirements and negotiate with a UK business partner. In that negotiation the UK partner has very little leverage - if the UK partner doesn't like terms Apple US is offering, Apple US can just find another partner. The UK partner then sells phones according to Apple's specification. The result is that the UK partner will have thin margins and almost all profit will flow back to the US. Unfortunately, tax law allows Apple to move its intellectual property to an Irish subsidiary company. The profit on UK sales is then booked in Ireland and Apple pays the low Irish tax rate even though the real profit has been generated in the US. I accept your point that 23% may be a good corporate tax rate - but in that case it should be 23% for all Californian companies, not just the ones which are able to transfer their IP offshore.