It’s a scam that’s been around for a while now but it’s still catching people out. You receive an email that suggests you’re entitled to a refund and then directs you to a legitimate looking site. Sometimes fraudsters will use this site to download software to compromise your computer – other times they’ll try to trick you into revealing bank details.
For the record – HMRC have said they will never email taxpayers about tax refunds. If you get an email like this then just delete it.
You can find more details on HMRC scams here