The US Treasury Department has upped the pressure on Europe over the Commission's investigations into the tax relationship between five large companies and a number of EU member states.
In a white paper issued on its website, the Treasury Department calls on the Commission not to impose recoveries in a retroactive manner from the companies under investigation, including Apple, Starbucks and McDonald's.
It believes this would 'set a bad precedent for tax policymakers around the world'.
The Department expresses concern that the Commission's State aid investigations threaten to undermine progress on a number of global initiatives that seek to clamp down on tax avoidance by multinationals.
It says state aid recoveries could have an outsize impact on US companies and that ultimately US taxpayers could end up footing the bill.
The biggest of the investigations centres on Apple's tax dealings with Ireland.
The US tech company stands accused of benefiting from a number of tax rulings here.
The government, Revenue and Apple reject the accusations.
A ruling is expected to be made on the Apple case in September or October.
The Minister for Finance has vowed to appeal any adverse ruling to the European Court of Justice in Luxembourg.
Last year, the European Commission ordered the Netherlands to recoup €30 million of unpaid taxes from Starbucks.
The Dutch government says it will appeal the decision.
