Mobile phone giant Vodafone, based in Newbury, faces a fresh tax row after it emerged that it paid no corporation tax in Britain last year.
The firm earns several hundred million pounds from its 19 million UK customers but shared none of these with HM Revenue & Customs (HMRC), according to an investigation by the Sunday Times.
The company said its corporation tax liabilities in its home country were offset through investment in improving its network and by interest costs.
The group has previously been criticised for its dealings with the taxman after its £1.2 billion settlement of a decade-long dispute with HMRC in 2010.
Underlying earnings at Vodafone's British operation rose from £1.2 billion to £1.3 billion in the year to the end of March, while adjusted profits rose 16% to £402 million. Yet its corporation tax bill fell from £140 million to zero.
Vodafone said its UK capital investment increased to £575 million from £516 million in the year, meaning it spent more than £1.5 million every day on improving its network and IT systems.
Its UK business accounts for less than 4% of group profits and it paid the exchequer about £700 million in payroll and other taxes last year.
A Vodafone spokesman said: "As in most countries, there are tax reliefs for capital investment and interest costs in the UK, which applied in this case.
"We paid £14 billion into the public purse worldwide in 2011 if one includes payroll and sales taxes as well as fees for radio spectrum."
Vodafone's global corporation tax bill rose by about £300 million to £2.3 billion last year, which is in line with other British multinationals.