Some highlights of the Roadmap: Replace Medicare with a voucher-based system, get rid of the corporate income tax and replace it with a consumption tax, offer a simplified income tax system and personal investment accounts as an alternative to the current Social Security system.

FORBES: Should Rep. Paul Ryan's Roadmap Be Taken Seriously? Weigh In.

In the US system the corporate income tax is levied upon dividends first and then dividends are taxed again at the individual level.

FORBES: Taxing Capital Isn't About Fair: It's About Efficiency

Like other U.S. companies, Apple pays an extreme tax penalty for bringing its foreign profits home to invest in the U.S. This is due both to the punitive U.S. tax rate and the fact that the U.S. is virtually alone in refusing to embrace a territorial tax system that applies corporate income taxes only in the jurisdiction where the money is earned.

WSJ: Review & Outlook: The Apple Tax Diversion

Romney would shift the corporate tax to a territorial system in which domestic firms owe no U.S. income tax on their overseas sales but foreign firms pay U.S. tax on money they make here.

FORBES: The 10 Biggest Differences Between The Romney And Obama Tax Plans

Foreigners are attracted chiefly by Malta's tax system, which allows income tax on dividends to be offset against corporate tax, reducing the effective tax rate on dividends from 35% to 5%.

ECONOMIST: How the euro and technology are changing an island economy