The records of up to 100,000 taxpayers have been accessed by organised criminals following an attack on HMRC.
The tax authority is thought to have lost £47million as a result of the breach last year, with 0.2% of PAYE taxpayers with personal accounts affected - representing around 100,000 people.
Officials told the Treasury committee that the incident was "not a cyber attack" but instead opted for multiple phishing attacks "designed to extract money" from the tax authority.
HMRC is writing to those affected to confirm it has secured their accounts, they haven't lost any money, and they don't need to do anything.
"These are attempts to claim money fraudulently from HMRC, not from customers," HMRC said.
Angela MacDonald, HMRC's deputy chief executive, told MPs on Wednesday that a "lot of money" was taken and "it's very unacceptable".
Read the full story in The Telegraph.
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