A Ukrainian man who defrauded the tax authorities of £560,000 has been sent to jail for three-and-a-half years.
Dmytro Shepel, a 25-year-old illegal immigrant, obtained the money by setting up 350 false identities on the tax self-assessment system.
He used 218 of them to make bogus tax reclaims and tried to steal £646,000.
Shepel was convicted at Woolwich Crown Court and will be deported at the end of his term in jail.
He had carried out his fraud while working under a false identity as a Lithuanian.
Using a false passport he opened 74 bank accounts in the space of two years to receive the fraudulent tax rebates.
"In common with commercial financial organisations, we face attempts by individuals and organised criminals to steal from us and we have processes in place to detect and counter fraudulent repayments claims," said Simon Grunwell of HM Revenue & Customs.
"These are kept under constant review to ensure we are able to deal effectively with ever-evolving threats."