There is currently a scam email doing the rounds, similar to this:
Remember that the HMRC will never send notifications of tax refunds or ask you to disclose personal or payment information by email or text message.
If you receive this type of email and you’re not sure of its legitimacy, forward a copy of it to the email address below.
The HMRC will determine whether it’s a scam and their specialist team will investigate and take the necessary action.
HMRC publicizes details of current scams on their website: https://www.gov.uk/government/publications/phishing-and-bogus-emails-hm-revenue-and-customs-examples