Schenk, Alan and Oliver Oldman, “Value Added Tax, A Comparative Approach,” Cambridge University Press, New York, NY, 2007

“According to the WTO rules, border tax adjustments for indirect taxes do not constitute subsidies of exports or disadvantages to imports,” p. 6.  

(VATinfo Note: The U.S. by not having a VAT, since all its trading partners do have one, is at a competitive disadvantage by not subtracting the cost of government from exports and not adding the de facto tariff of a VAT to imports.)