HM Revenue and Customs (HMRC) said that 23,247 phishing emails were reported to it in the three months leading up to the online self-assessment deadline on January 31 - a 47% increase on the same period a year earlier. During 2013, customers reported more than 91,000 phishing emails to HMRC.
Emails sent as part of the scam often begin with a sentence such as: "We have reviewed your tax return; according to our calculations of your last year's accounts a tax refund of (an amount of money) is due."
The conmen behind the emails try to trick victims into handing over their bank account or credit card details. Typical details requested in these emails include the victim's name, address, date of birth, bank account number, sort code, credit card details, National Insurance number, passwords and mother's maiden name.
Anyone responding to this type of email risks opening their bank account to fraudsters and having their details sold on to other organised criminal gangs.
The revenue body said that in 2013 it closed down 1476 websites sending scam phishing emails.
Legitimate tax rebate forms from HMRC, called P800s, will contain a payment order and will never ask for credit or debit card details.