Fraudsters are using a lack of transparency in the UK's tax system to steal people's money, an expert has said.
Chas Roy-Chowdhury of accountancy body ACCA said ordinary taxpayers were the weak point in the battle against fraud.
They should not be criticised, he said, as con artists were exploiting the lack of interaction with the authorities.
On Wednesday, the BBC revealed how fraud reports to HM Revenue and Customs (HMRC) had risen sharply.
BBC Radio 5 Live's Wake Up to Money reported that cases had risen to about 85,000 a month now, compared with 70,000 on a typical month last year.
These are cases when fraudsters contact potential victims via phone, text or email, claiming to be from HMRC, and often suggesting people are owed a tax refund or need to pay more.