MPs have condemned the tax avoidance measures of big multinational companies like Starbucks as an "insult" to British businesses.
A report from the Commons' public accounts committee out today judged the aggressive tax avoidance practises, which are costing the UK billions of pounds, to be "outrageous" and "immoral".
Chancellor George Osborne is expected to unveil new funding for HMRC boosting the part of the organisation which deals with tax avoidance by multinational firms.
The move is an unusually direct response to today's report by MPs. Committee chair Margaret Hodge said: "There is little credible information about what is going on. The evidence we took from large corporations was unconvincing and, in some cases, evasive. HMRC also lacked clarity when trying to explain its approach to enforcing the corporation tax regime."
Representatives from Google, Amazon and Starbucks all faced a grilling from the committee's panel earlier this month.
At one point Andrew Cecil, Amazon's representative, was laughed at and ridiculed by the panel, with Hodge telling him: "They've sent you up as I don't know what. You're not serious. It's outrageous."
Starbucks has faced major criticism for its tax policy as the company has paid just £8.5 million in corporation tax since 1998, despite a turnover of £3 billion in its UK coffee shops.
It does this by buying all its coffee from the company's Swiss operation at a mark-up of 20% - effectively wiping out the profit of its UK arm, meaning it pays little or no tax here.
The rate of corporation tax in Switzerland is just 8.5%, compared to 24% in the UK (though this is set to fall to 23% next year).
Yesterday Starbucks issued a statement acknowledging that it needs to review its tax arrangements in Britain.
"We have listened to feedback from our customers and employees, and understand that to maintain and further build public trust we need to do more," it said.
"As part of this we are looking at our tax approach in the UK."
Starbucks has been warned against setting a "serious anti-business precedent" by paying more in tax than it is legally required to, however.
Nigel Green, chief executive of the financial consultancy DeVere Group, said the Starbucks board may breach its fiduciary duty by not legally mitigating its tax liabilities to its shareholders.
"A tax system which is based on 'donations' as a result of blistering attacks from MPs on a handful of high-profile companies, could deter foreign firms from investing in the UK," he said.
"Indeed, in many ways, the whole saga flies in the face of Mr Osborne's message that 'Britain is open for business'."
Labour said the funding announced today by the chancellor was a "tiny proportion" of over £2 billion of spending cuts to HMRC imposed by the coalition, however.
"If the government was serious about tackling tax avoidance, they'd rethink their plan to cut a further 10,000 HMRC staff, which risk being a false economy," shadow Treasury minister Catherine McKinnell said.
"Despite all the rhetoric about tackling tax avoidance, the progress made by this government is limited at best.
"The deal struck with Switzerland is less transparent than a similar deal struck with Liechtenstein by the last government."
Tax avoidance is legal in the UK, unlike tax evasion, which is a criminal offence and often carries a custodial punishment. The government has promised to introduce a law against general tax avoidance, which could be introduced in next year's Queen's Speech.