The findings suggest that thousands of partners across the UK now work in what accountants have called 'zombie practices' - and that for thousands more the risks, responsibility and workload that come with running a practice are not matched by the financial rewards.
The majority of partners (52%) who responded to the poll said they earn less per clinical session than locums at their practice - and one in seven (15%) said they earn less than salaried GPs at their practice, according to the latest GPonline opinion poll.
The poll, which received responses from 400 GPs, including 134 partners, suggests that around 1,000 GP practices nationally may fit the 'zombie practice' definition - those with profit per partner below the cost of employing a salaried GP for eight sessions per week. The term has been borrowed from the business world, in which a zombie company is one able to limp along paying its bills, but struggling to make any significant profit or bring down any debts it may have.
The poll also found strong support for a guaranteed minimum income for GP partners - with 82% of all respondents to the poll saying they would back this move. The GP contract in Scotland will introduce a minimum income per partner of just over £80,000 from April 2019 - although this is not understood to be an option on the table for England.
Meanwhile, two thirds of partners responding to the poll and one third of all GP respondents said salaried and locum GP pay should be capped at a level below partners' income.
The findings come as Dr Nigel Watson, the senior GP chairing a review of the partnership model commissioned by the government, prepares to publish interim findings from his review in October.
Dr Watson said earlier this year that the risks of partnership currently outweighed the rewards for many partners. Official data reveal that many GPs are voting with their feet - with the number of GP partners in England falling by more than 2,500 since September 2015 alone - a 10% drop.
GPonline reported last year on figures from accountants that suggested as many as one in five GP practices may be 'zombies' - and workload continues to put chronic pressure on the profession, with practices delivering an estimated 1m appointments a week over the level experts consider safe.
GPC chair Dr Richard Vautrey told GPonline that partners should earn more than either salaried GPs or locums to reflect the risk, responsibility and workload involved.
'You are carrying a significant degree of risk, a large responsibility - running the business, making decisions and ultimately the buck stops stops with the partners,' he said.
He said the BMA was aware that partners in many practices were earning less than locums or salaried GPs, and warned: 'Where that is the case partners may very quickly think it is no longer worth their while, and in those situations we have seen practices close.'
However, Dr Vautrey said he would not support a cap to keep locum or salaried pay below partners' income, or a guaranteed minimum income for partners.
Doctors who wanted certainty around income should consider salaried roles, he said, arguing that he could not see how a guaranteed minimum income could work within a partnership model. 'I think you need to recognise that it has degree of responsibility and risk and potential for variable payment, as with any other business,' he said.
However, income for partners in England in 2016/17 was 22% below the level they received in real terms in 2005/6, official data show. The RCGP and BMA have both long called for general practice to receive a greater share of the overall NHS budget - a view shared by the partnership review chair Dr Watson.
The BMA called the 2% pay rise awarded to GPs by the government for 2018/19 'deeply concerning'.