The vast majority of council tax payers in Norfolk and Lowestoft were last night promised lower bills under controversial plans to create a single super-council.

The vast majority of council tax payers in Norfolk and Lowestoft were last night promised lower bills under controversial plans to create a single super-council.

Norfolk County Council yester-day set out for the first time how the council tax take would fall by £5.25m if the plan for a single authority were given the green light, insisting it would mean lower bills for more than 600,000 residents.

It said its overhaul to replace the county and district councils with one authority would cost £18.65m, which would be paid back in three years.

And it would see falls in the average band D council tax bill of between £1 a year and £104.

But band D householders in Breckland, who have historically had the lowest district council tax bills, would pay £46 a year more under proposals to even out the tax take across the county.

Supporters of the one-council plan believe that the savings will not only help cut bills but will also free up nearly £25m a year for investment in extra services.

And that is likely to be a conservative estimate as the business case does not consider the possible windfalls from selling off redundant council buildings and assets.

It would also see 530 staff jobs shelved as posts like service directors are streamlined and admin staff like IT and human resources are merged.

But critics also claimed that it would need a £5m cut in services to make it pay.

Last night a joint statement by the leaders of five district councils - Breckland, Broadland, King's Lynn and West Norfolk, North Norfolk and South Norfolk - said the single council business case, which does not include parish or town council precepts, was “simply not credible”.

Meanwhile Norwich City Council, which is working up a rival bid for a greater Norwich council, said it would deliver a £50-a-year saving for city-based council tax payers and would also yield an extra £15m investment in greater Norwich schools.

And the leader of Yarmouth Borough Council, which is working up a case for an authority covering a “wedge” of Norwich, Lowestoft and Yarmouth, claimed the super council lacked accountability and would turn local government into a “smaller version of the EU”.

A final judgement about the business case will be made by the Boundary Committee which will unveil its final preferred option and conclusions for ministers for consider at the end of the year.

David White, chief executive of Norfolk County Council, whose business case report will be discusses at a special council meeting on Monday, said: “Bringing eight Norfolk councils, plus Lowestoft, together to work locally as one offers the biggest potential for savings and the greatest scope for efficiency.

“Clearly, the level of council tax would be for members of the new authority to decide. But our work clearly demonstrates that with projected annual savings of £24.59m, they are able to reduce the overall tax burden by over £5m a year and still be able to invest more in improving public services.”

But district council leaders said their finance officers had been unable to verify the figures, which are due to be submitted to the Boundary Committee, tomorrow.

“On the face of it the county councils figures are simply not credible,” their statement said. “We believe that the county have understated the set up costs and over estimated the savings.

“As the leaders of the majority of Norfolk's district councils we will strongly oppose these proposals for unitary local government structures in Norfolk. Such proposals are bad for democracy in Norfolk, bad for services in Norfolk and bad for council tax payers in Norfolk. We challenge the county council to tell us the last time that a re-organisation of local government actually saved money or resulted in lower council tax bills.

Alan Waters, executive member for resources and governance at Norwich City Council, said the super council plan would mean £5m in service cuts.

“Under the 'doughnut' option, council tax would also be reduced but the new councils would still offer service improvements. In greater Norwich an additional £15m would be available to spend on schools, where extra investment is urgently needed.

“We remain convinced that a one super council for the whole of the county and Lowestoft in Suffolk covering a population as large as that of Cyprus would be remote, undemocratic and unable to focus on the specific needs of local areas. Meanwhile, the loss of Norwich's strong identity and historic status for the sake of a £1 per week council tax reduction for Band D householders would impact on its role as an economic driver not just for Norfolk but the whole region and its ability to attract crucial investment.”