In the case of Amazon at least, some tax experts said that in conducting a wide range of activity in the UK, it may be on the wrong side of the hitherto undefined boundary.
Yet Jacques Sasseville, head of the tax treaty unit at the Organisation for Economic Co-operation and Development, which advises rich nations on tax policy, said he was not sure if a boundary exists.
He said where sales were conducted online, it was almost impossible to prove a taxable presence in a jurisdiction, irrespective of how much activity is conducted in that country.
Member of Parliament Margaret Hodge said she wanted HMRC to look more closely at the company’s affairs, to see if Amazon was paying all the tax it should.
She also said she planned to call Amazon representatives back to testify to the committee which she chairs and clarify written evidence and witness testimony the firm gave in November last year, in which it downplayed its activities in Britain.