There are some e-mails going around that are, supposedly, from HM Revenue & Customs. They "inform" you of your tax rebate and ask for some information so that they can "pay" you (one e-mail has a link for you to click to claim that opens a site in your browser that is a phishing site).
A quick look at the "forms" that are a part of the e-mails tells me that they are fraudulant forms as they are asking (among other things like mothers' maiden name) for your card number AND the security number from the rear of the card. Regular readers will already be aware (from the Credit Card Phone Scam page) that the 3 security numbers on the back of the card should ONLY be used when you are ordering something over the phone or on-line. In fact, if the money were to be paid to your bank account, all that is required is your Name, Sort Code and Account Number, nothing else!
Do NOT visit the website contained within the email (if a link is given). Do NOT disclose any personal or "payment" information. HM Revenue & Customs know where you live and would advise you in writing via the postal service if you were due a rebate. They would not contact you by telephone, e-mail or any other means.
For more information on this and other scams that are, supposedly, the HM Revenue & Customs getting in touch with you see the HM Revenue & Customs sites' page on scams.