GPs are on course for a lucrative average quality score of between 920 and 950 points.
GPs are 'overperforming' and will score far more points than expected, says Chris Town, head of the NHS's contract negotiating team.
Although most practices aspired to more than 900 points, both GPC and NHS Employers' negotiators thought their achievement would be lower.
But Mr Town said evidence from his recent meetings revealed GPs were on track to meet their aspiration levels.
However, he warned PCTs were facing 'serious financial difficulty' because the Government failed to give them enough cash to pay for GPs' achievements.
Ministers only budgeted for GPs to score an average of
777 points, meaning trusts
will have to find around £100 million extra to cover the gap.
The Department of Health reiterated this week GPs would be paid for their full achievement but that PCTs would get no more money.
A spokesman said the NHS was 'used to managing risk on its budgets'.
But GPs fear trusts will raid other primary care funds to meet the extra cost.
GPC negotiators warned in their December bulletin that a number of PCTs have deliberately underspent on enhanced services in order to cover the cost of the quality framework.
GPC chair Dr Hamish Meldrum said trusts would not be allowed to dip into other budgets. He said: 'We fought hard to make sure the contract was not flexible, so money cannot be taken from other areas in general practice to pay for any shortfall.'
Dr Meldrum added the high scores showed GPs were doing 'an excellent job'.
Dr Ian Trimble, PEC chair of Nottingham City PCT and a GP in the city, said trusts were more likely to find the savings by closing hospital wards.
He also criticised the Government for failing to realise GPs would score more than the 777 point average.
He said: 'Any reasonably well-organised practice can get 950 points, but instead the Government predicted practices would get far less than the maximum 1,050 points.'
The Government cut the pot of money available for quality pay in order to finance the MPIG.
A spokesman for the Scottish Executive said GPs north of the border were also over-performing against the framework. The Auditor General revealed last week the expected cost of the contract would be £83 million, up from £53 million, as a result of out-of-hours costs and higher quality pay.
By Anna Goldie