John Christensen, executive director of the Tax Justice Network, thinks the £130 million payment is nowhere near enough.
"We're seeing an effective tax rate for the current deal for 2005 to 2014 of around 3 percent. We think it should be far higher," he said, pointing out that the nominal tax rate for most of that period was well in excess of 20%.
"There should be some transparency about how they arrived at this settlement," he said.
While Christensen welcomed Hillier's intention to call Google and HMRC before the U.K. parliament's Public Accounts Committee, he wants a more thorough investigation from the U.K.'s National Audit Office, which scrutinizes public spending and tax collection.
Google did not respond to a request for comment.
It will be a while before any details of its U.K. tax settlement filter through into its public filings. On Sept. 16, 2015 Google filed notice that it had extended its 2014 fiscal year to end on June 30, 2015. Those figures are still to come, while Friday's settlement may appear in the filing for its 2015 fiscal year ending June 30, 2016 -- and which need not be filed until 2017.
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