Meanwhile the UK's salaried GPs' pay has risen by 3.4% to £55,790 over the same period (2006/7 to 2007/8).
Despite GP partners' gross earnings rising by 1.9%, total expenses have leapt 4.5% over the same period, causing income to fall.
The average GMS partner earned £100,324 in 2007/8, while PMS partners earned £116,059.
GPs in Wales have been hit hardest, where average income fell 4.5% to £93,336 in 2007/8.
As usual, G/PMS partners in England were the highest paid, earning an average of £110,139, while their equivalents in Northern Ireland earned the least £91,056.
The average expenses for a G/PMS partner were £145,925 in 2007/8, a figure overlooked in the Daily Mail's controversial front page story claiming GPs were earning up to £380,000 a year, based on gross earnings alone.
All statistics are pre-tax and based on HM Revenue and Customs data.