From 6 April, the so-called 'fit note' will allow GPs the option to advise a patient that they 'may be fit for work'.
The GP would then be able to suggest ways that the patient could be helped to return to work sooner, for example by adapting the workplace.
Dr Bill Gunnyeon, chief medical adviser to the Department of Work and Pensions, said he realised some GPs were concerned about not having the skills to meet the new requirements.
'We are not asking GPs to make recommendations about the specific nature of the job. What we are asking them about is the functional impact of the patient's condition and anything they think of that might help the patient return to work.
'It is then for the employer to decide whether they can make those adjustments or not.
'If they cannot return to work, then the certificate they have from the GP enables them to not return to work. There is no requirement for them to go back to the GP for another statement. The employer has effectively taken responsibility.'
London GP Dr Alan Cohen, national primary care adviser for Improving Access to Psychological Therapies, welcomed the new procedure as an early intervention to prevent patients slipping in to long-term sick leave and developing secondary conditions.
But he added that GPs needed better access to the relevant specialist services: 'It's all very well telling the patient that going back to work is helpful for their health but then they have to wait two or three months for psychological therapies or physiotherapy.'
For further guidance on fit notes, visit www.dwp.gov.uk/fitnote