The note was unveiled by the DoH last week and allows GPs to advise employers on what patients can do at work, replacing sick notes.
But Dr Robert Hampton, a GP from Leicester who worked on the note's design group, said GPs would have to ask detailed questions about what patients did at work to complete it properly.
'I could see there being a 50/50 split between GPs who are comfortable with this and those who felt it falls outside their duty of care,' he said.
The new, computer-printed form will allow GPs to tick 'you may be fit for some work now' and suggest a phased return.
GPC chairman Dr Laurence Buckman said GPs should not have to decide if patients are ill enough to receive benefits.
But Dr Hampton said the forms could reduce 'the burden on GPs as judge and jury', by encouraging discussion bet-ween patients and employers.
The consultation on the note closes on 19 August.