US federal corporation Tax
US federal corporation tax is 35%, while the UK's rate is 21% and is due to be cut to 20% in 2015.
But Ms Self added that a significant tax gain for the UK would be unlikely.
"All it will mean is moving a few senior people here and having a few board meetings here. It doesn't mean anything for the UK tax industry," she said.
Labour shadow business secretary Chuka Umunna expressed concerns over job security for AstraZeneca staff.
"Pfizer has a very poor record on previous acquisitions. Do we really want a jewel in the crown of British industry, our second biggest pharmaceutical firm, to basically be seen as an instrument of tax planning?" he said.
Union worries
The GMB union, which represents workers at AstraZeneca's Macclesfield plant, called for the proposed deal to be investigated on competition grounds and queried Pfizer's promises over UK jobs.
"Pfizer are said to have given undertakings to the UK Government as they increase the money they are offering the AstraZeneca shareholders," said Allan Black, GMB national officer for the chemicals industry.
"Similar undertakings were given by US multinationals before which have proved to be worthless."
The GMB also questioned how committed Pfizer was to manufacturing and R&D in the UK. In 2011, Pfizer laid off 1,500 staff from its research facility at Sandwich in Kent.
"Pfizer walked away from a purpose built manufacturing plant in an economic bleak spot in Kent with the loss of many jobs," Mr Black said.
The Institute of Directors (IoD) said that the government should not be involved, as the matter is for directors and shareholders to decide.
"The IoD does not support any extension of any national interest test for takeovers," said IoD director of corporate governance Roger Barker.
"Takeovers are primarily a matter for boards and shareholders to determine, not government."
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But Ms Self added that a significant tax gain for the UK would be unlikely.
"All it will mean is moving a few senior people here and having a few board meetings here. It doesn't mean anything for the UK tax industry," she said.
Labour shadow business secretary Chuka Umunna expressed concerns over job security for AstraZeneca staff.
"Pfizer has a very poor record on previous acquisitions. Do we really want a jewel in the crown of British industry, our second biggest pharmaceutical firm, to basically be seen as an instrument of tax planning?" he said.
Union worries
The GMB union, which represents workers at AstraZeneca's Macclesfield plant, called for the proposed deal to be investigated on competition grounds and queried Pfizer's promises over UK jobs.
"Pfizer are said to have given undertakings to the UK Government as they increase the money they are offering the AstraZeneca shareholders," said Allan Black, GMB national officer for the chemicals industry.
"Similar undertakings were given by US multinationals before which have proved to be worthless."
The GMB also questioned how committed Pfizer was to manufacturing and R&D in the UK. In 2011, Pfizer laid off 1,500 staff from its research facility at Sandwich in Kent.
"Pfizer walked away from a purpose built manufacturing plant in an economic bleak spot in Kent with the loss of many jobs," Mr Black said.
The Institute of Directors (IoD) said that the government should not be involved, as the matter is for directors and shareholders to decide.
"The IoD does not support any extension of any national interest test for takeovers," said IoD director of corporate governance Roger Barker.
"Takeovers are primarily a matter for boards and shareholders to determine, not government."
Share this story
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