Around one in 10 PMS practices could return to a GMS contract without incurring a financial loss, medical accountants have estimated.
The analysis comes as a GP investigation reveals that at least 1 per cent of PMS practices have returned to GMS contracts since 2008.
Responses from 59 PCTs show that 35 practices have switched back. If this rate is occurring nationally, around a hundred practices may have abandoned the local contracts.
This figure may rise, with 83 per cent of PCTs set to review PMS deals this year or next.
Bob Senior, head of medical services at accountancy firm RSM Tenon, said a return to GMS is more attractive because fewer GMS practices now rely on MPIG.
Mr Senior said what was once extra income for PMS practices was now available to GMS practices under local enhanced service (LES) deals.
'Practices need to look carefully at their particular locality, but I would be surprised if many of PMS practices' services could not be carried out as a LES under GMS,' he said.
Mr Senior added that some PMS practices were willing to take a financial hit to return.
'Some PMS practices have been downtrodden by PCTs. They have been picked at year after year, so if they can return to GMS at a modest cost they would be prepared to,' he said.
Mr Senior said practices may look to return to GMS as PMS reviews get underway.
'We may see a high proportion of practices looking at going back to GMS contracts,' he said.
Dr James Kingsland, president of the National Association of Primary Care, said PMS practices should not be forced out inappropriately.
But he added: 'I hope practices that adopted PMS contracts because of a service need will be able to make their case to the PCT.'