Last week GP reported DoH plans to take 60 quality framework points, worth £7,476 to the average practice, from the clinical domain and use them to fund extended hours.
Dr Smith has devised guidance on the costs of opening until 8pm four nights a week and from 9am to 11am on Saturdays. The annual cost of extended opening hours was calculated to be £6,032.
However, the figure is likely to spark controversy because it relies on GPs and nurses adjusting existing working arrangements to cover the extended hours at no extra cost.
GPs have questioned whether taking money from the contract and allocating it to work in hours outside the contract is legal.
The figure may ease concerns that 60 points is not enough to cover the additional hours. Doctors are alarmed by the prospect of a £7,500 pay cut if they do not offer the opening hours.
Dr Smith, however, said he had been running extended opening hours at The Churchill Medical Centre in Kingston, Surrey, for nine months and described it as 'fabulous'.
'It has been incredibly well appreciated by the patients,' he said.
'It seems inevitable that it would feature in the framework. There is no great evidence it produces better clinical outcomes, but we are seeing a lot of males in the evening whom we would not usually see.'
The guidance says the cost of extra hours 'is worth every penny' and flexible hours 'can be liberating'.
The guidance also reassures doctors that no one will have to work 8am to 8pm.
The guidance was created in response to a large number of GPs calling for information about opening extended hours, Dr Smith said.
'It was produced purely co-incidentally and just happens to have a cost figure near the one GP published for the framework points value,' Dr Smith said.
Dr Smith's leaflet will feature a six-step plan on how to achieve a successful extended hours service.
However, GPC negotiator Dr Chaand Nagpaul said he did not believe that refusing to pay staff to work unsocial hours could or should be the basis for a national policy.
How to run extended hours for £6,032:
Six additional weekday hours £60
Increased rate for two hours on Saturdays £26
Annual cost (£86 x 52) £4,472
Per year £1,560
GPs and nurses working flexibly for no extra pay during these periods.