Just how much? About $490 million that would be used to develop and make new meds unless the UK government quickly puts in place some new tax breaks. Glaxo likes the planned tax incentives on income from patents, but warned these should apply to drugs already under development, The Financial Times writes.

The UK’s Department for Business, Innovation and Skills, however, claims policies announced this week by Alistair Darling, the chancellor of the exchequer, were “already delivering major investment decisions,” and made a point of noting more than $800 million in investments planned by Glaxo (see the statement).

But there’s a bit of disagreement. In its own statement, Glaxo indicated that a $325 million for production of new respiratory meds had already been planned for its Ware, Hertfordshire, facility, and another $490 million for a plant at one of its six UK locations has not been finalized.

The UK’s so-called “patent box” announced this week would offer, as of 2013, a reduced rate of 10 per cent tax on revenues generated by patents based in the UK. On current plans, the tax break would apply to patents filed from 2011.

“The patent box is exactly the sort of active, long-term and creative support that we need from government,” Glaxo ceo Andrew Witty, says in his statement. “Assuming the new regime will apply to patents currently under development, it will have the immediate impact of making the UK a priority area for future investments.”

Glaxo is still debating alternative locations for late-stage development and manufacture of its next generation of drugs, at a time other countries such as Belgium, Ireland and Singapore have offered high tax incentives to encourage investment, the FT writes.

Lord Drayson, science and innovation minister, said of Glaxo’s request for patents to be recognized for the new incentives by 2011 at the latest: “We have taken that very seriously. It is something we are definitely working on.” And he stressed that industry demands for enhanced incentives had been heeded. “Now,” he tells the FT, “I expect industry to respond.”