Britons are having to work the first five months of the year before they stop earning for the chancellor and begin earning for themselves, according to data released on Sunday.

The Adam Smith Institute calculates that the average taxpayer worked 151 days a year just to pay taxes - three days later than last year and six days more than in 1997.

The thank tank calculates that every penny earned by the average British worker so far this year has been needed to pay taxes.

"It is astonishing that Gordon Brown has managed to make us all put in six days more work for the Treasury without many people noticing," said the institute’s director Dr Eamonn Butler.

"It is a tribute to his skill at dreaming up new stealth taxes.

"But he cannot escape Tax Freedom Day, which is a straightforward and clear indicator of just how much time we spend working to pay our taxes."