Your assumption is that the overhead is only a "one-time cost", but its never going to be that simple. Most of the time there are a multiplicity of overlapping

Your assumption is that the overhead is only a "one-time cost", but its never going to be that simple. Most of the time there are a multiplicity of overlapping cost; Opportunity cost (you have your money safely in a tax-haven, but now to move it out for legitimate production use has another cost and associated accountant / lawyer overhead). Or simply ongoing inefficiencies - You've opened an office in Country Z because doing so allows you to save on taxes in your main area of Country A, but the truth is you have no real need for an office in Country Z - its simply an ongoing and perhaps ever growing cost subject to a whole new need for budget forecasting, currency fluctuations, etc. I have no idea what the number is, but currency fluctuations alone could make a corporation decide to simply pay their 15% and escape headaches and split brainpower, trim staff of lawyers, consolidate offices, etc. Now, if the corporate tax rate is 36+% well, thats a different story.