Reform of corporate tax levels has emerged as a major election-year issue, with both sides battling to prove that their proposals will restore America’s competitiveness.

America’s corporate tax rate is currently one of the highest in the world. Republican presidential nominee Mitt Romney has proposed shifting to a territorial system, under which corporations would be assessed the domestic rate only on income from domestic operations. Foreign affiliates of American companies would take advantage of lower-tax jurisdictions abroad and compete on equal footing with foreign-owned companies.