The compensation bill for the NDR has risen to more than £23m as landowners put in claims for properties affected by the road.
Norfolk County Council's latest accounts warn that the compensation payouts are likely to rise further for the dual carriageway, which is now known as the Broadland Northway.
The final bill for the 12-mile dual carriageway from Postwick to Taverham is around £205m, which includes £18.7m set aside for compensation for buying the land for the project.
The council's 2018/19 accounts said the construction had resulted in a "large number" of claims and added the majority were yet to be finalised.
It said it had paid £567,000 in 2018/19 for compensation, with £135,000 the largest single amount paid. The figures were provided when we asked to look at the numbers which underpin the accounts as part of a project with The Bureau of Investigative Journalism.
The council did not provide the names of the landowners.
But it also warned a second type of claim for properties which had been devalued by the project was expected and the amount it would have to pay for that would likely rise.
The council has earmarked £4.5m to pay people whose land has reduced in value.
But the accounts said: "Given the long time-scales and complexities of negotiations this may be exceeded by the actual outcome."
A county council spokesman said: "The payment of compensation is a matter of law - we will receive and assess any claims and pay accordingly.
"The Broadland Northway is already proving to be a major benefit to motorists, to villages benefiting from less rat-running and to businesses looking to invest in the area."
Andrew Boswell, a former Green Party county councillor who opposed the new road, said: "Road projects never deliver to predicted costs as this latest news on the ever increasing NDR costs show."
He said the price tag should be a warning to the council as it looks to build the so-called 'missing link' which would connect the NDR to the A47 west of Norwich.
The council believes that link road would cost it £153m but campaigners have protested about the environmental damage it would cause.
Green Party city councillor Denise Carlo said: "The final bill for the NDR just keeps on rising. This is a shameful amount of public money when Norfolk County Council says it can't afford social care for the most vulnerable."
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