Bogus callers have been contacting residents in Lancashire offering them a council tax refund of £7,000.
The fraudsters claim to be from a local district council and tell residents they are entitled to a significant refund from their council tax.
They then ask for bank details and a £100 fee to process the refund.
Lancashire trading standards has said the caller is a fake and have urged people not to give out their bank details.
Paul Noone, Lancashire County Council's chief trading standards officer, said: "The main purpose of the scam is to obtain the victim's bank details or money.
"We would like to stress that these phone calls have no connection whatsoever with the district councils and their council tax collection functions."