EU state aid regulators opened an in-depth investigation on Tuesday into Amazon’s tax deals with Luxembourg, saying the arrangements could have underestimated the U.S. The European Commission said Luxembourg’s 2003 tax ruling for Amazon’s local subsidiary Amazon EU Sarl allowed the company to pay a royalty to its parent which reduced its taxable profit and might not be in line with market conditions. It said this could give Amazon an economic advantage by allowing the group to pay less tax than other companies whose profits are allocated in line with market terms.