MPs are questioning senior executives from multinationals Starbucks, Google and Amazon later on why they pay so little tax in the UK while racking up millions of pounds worth of sales.
The Commons Public Accounts Committee (PAC), which is charged with monitoring government financial affairs, has invited the companies to give evidence amid mounting concern about tax avoidance by big international firms.
Troy Alstead, Starbucks' chief financial officer, is answering questions from Labour MP Margaret Hodge, head of the PAC.
"I assure you we are not making money," he told the committee.
Matt Brittin, the chief executive of Google UK, and Andrew Cecil, Amazon's director of public policy,
Starbucks reportedly paid just £8.6m in corporation tax in 14 years of trading in Britain.
It was also revealed it paid no corporation tax for the past three years, despite sales of £1.2bn in the UK.
The coffee giant's UK managing director, Kris Engskov, told Sky News last month the firm had no plans to change its tax arrangements.
Google's UK unit paid just £6m to the Treasury in 2011 on revenue of £395m, according to The Daily Telegraph.
Earlier in the year, The Guardian reported Amazon - Britain's largest online retailer - generated UK sales over the past three years of between £7.6bn and £10.3bn, but paid virtually no corporation tax.
The three firms are among several which have had their tax affairs put under the spotlight recently.
Companies are able to sidestep the taxman legally by conducting different operations in different countries, and constructing complex global frameworks that allow them to move money through offshore subsidiaries and locations.
"It is hard for the ordinary person to believe it's fair," said Ms Hodge earlier.
"It makes people incredibly angry in the current fiscal climate," she added
Last week, HMRC defended itself against strong accusations that it is too soft on multinationals.
"I can refute any suggestion that we have been told to go easy on big business," Lin Homer, chief executive of HMRC, told the PAC.
Chancellor George Osborne joined his German counterpart Wolfgang Schaeuble last Wednesday in a call for "concerted international co-operation to strengthen international standards for corporate tax regimes".
However, Mr Osborne also insisted that those strong standards must not deter large international companies from making vital investments.