Income per patient varies from just £1.98 per patient for some practices to more than £36 per patient for others, figures from accountants Ramsay Brown and Partners show.
The variation means some average-sized practices earn more than £200,000 a year from enhanced services, while others barely reach five figures.
The top earners can generate twice as much income from enhanced services as they do from QOF, the data reveals.
Laurence Slavin, a partner at the accountancy firm, told GP newspaper that some practices with higher enhanced service income are in areas with high need, but many low earning practices are also in these areas.
The number of enhanced services practices choose to provide can also account for some of the variation, but much of it depends on their PCT's financial situation, said Mr Slavin.
'The attitude within the PCT is the most significant factor. PCTs see local enhanced services as a soft target,' he said.
Some practices would lose up to £35,000 from enhanced service cuts this year, warned Mr Slavin. Last month Haringey PCT, north London, took the unprecedented step of suspending all LES payments to practices with immediate effect.
The problem extends to Wales, where GPC Wales estimates that some local health boards spent just 20 to 30% of their share of a £5m funding package for enhanced services in 2008/9.
The DoH pledged a 1.5% increase in investment in enhanced services in England for 2008/9, but the GPC claims little has reached practices.
- Read this week's GP dated 11 September for the full version of this story.