The Government is warning taxpayers to beware scam emails and calls purporting to be from the taxman offering a rebate.
This follows the revelation that 5.7 million people on the Pay As You Earn system have paid the wrong amount of tax since 2008 due to an HM Revenue & Customs (HMRC) blunder.
Roughly 4.3 million are due a refund (see the 2010/11 Tax Breakdown guide).
Fraudsters are expected to step up efforts to extort cash, by sending out what are known as 'phishing' emails, or by calling taxpayers, following the saga which has dominated headlines over the past few days (see the Tax cock-up MSE News story).
HMRC stresses it never sends emails or calls anyone to inform them of a tax rebate. Any such communication will always be by post.
Chris Hopson, director of customer contact at HMRC, says: "We only ever contact customers who are due a tax refund in writing, by post. We never use telephone calls, emails or external companies.
"We strongly urge anyone receiving such a phone call not to give any information, but report it to the police straightaway.
"If customers receive an email claiming to be from HMRC, we recommend they send it to us for investigation before deleting it permanently."
HMRC says fraudsters typically try to gather your bank details, then attempt to take money from your account.
Victims not only risk having their accounts emptied but their personal details sold to other criminal gangs.
Scam emails 'offering' a tax rebate are nothing new (see the Tax scam warning MSE News story for an example email) and have been prevalent for years.
In August, HMRC reported a surge in the number of tax scam phishing emails. In the last four months, it has shut down over 180 websites responsible for sending out fake tax emails.
Scam networks have been closed in the UK, Austria, Japan, Mexico, South Korea, Thailand and the USA.
If you receive a suspicious email, forward it to HMRC at firstname.lastname@example.org and then delete it from your computer / email account.
Do not click on websites, links or attachments contained in suspicious emails.
Further reading/Key links
Protect your computer: Free Anti-Virus Software
Tax tips: 2010/11 Tax Breakdown
HMRC advice: Tax rebate email warning