Which means of course the big multi-nationals are paying 35%. Except for one problem - they can "move" earnings to other national jurisdictions where the income tax rate is somewhere between 15% and 25%. So of course, they move heaven and earth to not pay taxes in the US, so they can pay lower rates elsewhere. So that means that multi-nationals in general have a very low effective tax rate in the US - because they'd prefer to pay the lower taxes in other jurisdictions. I think I have recently seen as low as 5%.

That's Boca's point - for many companies, like Microsoft, lower US corp income tax rates so they are competitive with places like Ireland, and the effective tax rate paid to the US should be expected to increase (because why would Microsoft move heaven and earth to shift earnings to Ireland if they can pay similar rates in the US?).