Police think a bogus caller visiting homes in Kent is getting information from people he could use to later defraud them.
It is thought there have been six recent incidents where a man has called at houses claiming to be doing a survey for Kent County Council.
He has asked for details about the people's wages and persuaded some of them to give him their signature.
But officials from Kent County Council and Thanet District Council warned they do not conduct such surveys.
The man has called at homes in Minster, Westgate and Margate.
He has asked how much the homeowner earns, where they are employed and what hours they work, before going on to ask for their signature.
Kent Police said it was likely the information would be used to steal from the properties while they are empty or to steal from bank accounts.
They have urged people to check the identity of callers and not to give out personal details.
The man is described as having a Mediterranean appearance, about 5 ft 6 ins tall, aged in his 30s, clean shaven, with dark hair and a local accent.
A woman who has sometimes accompanied him is described as in her late teens, white, with long dark hair.