Labour has been accused of blundering with a poster suggesting that the Coalition has put up VAT on food.
The campaign accuses David Cameron and Nick Clegg of adding £450 to shopping bills by increasing the levy.
The Tory and Liberal Democrat leaders are depicted as "peas in a pod", surrounded by images of everyday goods including fruit and vegetables, soft drinks, ketchup and biscuits.
But critics have been quick to point out that many of the items portrayed are in fact exempt from VAT - and so were not affected when the standard rate rose from 17.5% to 20% in 2011.
Most food and drink for human consumption is zero-rated, although the duty is charged on specific products such as alcohol, crisps and savoury snacks, and confectionery.
Tory MP Henry Smith said: "It's the same old economic incompetence from Labour. They have no long-term plan to fix the economy so instead Ed Miliband resorts to political gimmicks that don't even add up."
A Labour Party spokesman said: "David Cameron and Nick Clegg are desperately trying to deflect from the truth of their VAT bombshell.
"Their decision to increase VAT has added £450 to family bills over the year, on the Treasury's own figures.
"Families are paying more on their typical weekly shop as a result of the Tories and the Lib Dems and this poster rightly holds them to account.
"It is not an itemised list of everything they have increased VAT on - it is a representation of an average shopping basket."