THE average Huddersfield household will pay more than £65 a year if the proposed elected Assembly for Yorkshire and Humber goes head, according to the Yorkshire Says No campaign.
The pressure group is calling on people to reject the Assembly in the autumn referendum.
Chairman John Watson said: "We know that Ken Livingstone's regional council tax levy in London is already £230 per year for an average property.
"We also know that council tax bills in Wales have risen by more than £100 at the behest of the Welsh Assembly."
He said a White Paper published two years ago claimed that the annual administrative cost of running the Assembly would be £25m - or £13 per household in Yorkshire and Humber.
"Such a figure now looks indefensibly low and does not include money the Assembly could raise in a levy on council tax.
"It's terrible value for money," said Mr Watson.