Big companies can book big tax savings by creating complicated accounting and legal structures that move profits to low-tax Luxembourg from higher-tax countries where they’re headquartered or do lots of business. In some instances, the leaked records indicate, companies have enjoyed effective tax rates of less than 1 percent on the profits they’ve shuffled into Luxembourg. The leaked documents reviewed by ICIJ journalists include hundreds of private tax rulings – sometimes known as “comfort letters” – that Luxembourg provides to corporations seeking favorable tax treatment.”