A TV licence email scam has led to more than 5,000 complaints over the past three months.
Cyber crime monitor Action Fraud said fake TV licence emails regarding payment issues had been sent out to try to collect bank details.
The number of reports has increased in each of the past three months, with 1,805 complaints in December alone.
Action Fraud told the BBC the scam was "particularly nasty as it looks so convincing".
The emails use headlines such as "correct your licensing information" and "your TV licence expires today" in an attempt to convince people to click on the link in the email.
Action Fraud said it received 5,057 complaints about such emails between 1 October and the end of December.
While the emails themselves might vary slightly in their wording, all of the links direct through to the same website.
The fake TV Licensing website asks victims to provide their payment details, including their account number, sort code, and card verification value (CVV) code on the back of their card.
The website may also ask for a victim's name, date of birth, address, phone number, email and possibly even their mother's maiden name.
Action Fraud said it was working to "stop fraudsters in their tracks".
A TV Licensing spokeswoman said: "TV Licensing will never email customers, unprompted, to ask for bank details, personal information or tell you that you may be entitled to a refund."
The sender's email address - does it look like one TV Licensing would use?
If you think you have received an email from fraudsters, you should report it to Action Fraud.