The overhaul is designed to stop people drifting into extended sick leave and is based on evidence showing that work is good for health.
Fit notes have been tested by more than 500 GPs at a range of practices and have won positive feedback, the DoH says.
Speaking at the launch of the scheme in central London this week, health secretary Alan Johnson said the current sick note scheme, unchanged since 1948, had 'no flexibility'.
'I am pleased that GPs and the BMA are behind the launch of the fit note,' he said.
GPC deputy chairman Dr Richard Vautrey said GPs did not want to become an arm of the Benefits Agency, but recognised the health benefits of returning to work.
However, work and pensions secretary James Purnell stressed that he was not expecting GPs 'to police the system'.
Meanwhile, the DoH and RCGP have produced guidance to train GPs to handle work issues, which will be available from April 2009.
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