The Public Accounts Committee has criticised HM Revenue & Customs for its "unacceptably slow" action against tax avoiders.
Margaret Hodge, chair of the committee, said the inaction was putting tax revenues at risk: "HMRC must do more, faster."
She highlighted that a tax avoidance scheme closed down in 2009 was not taken to a tribunal until this year.
"This may be just the tip of the iceberg," Mrs Hodge said.
Up to £10m of taxes avoided by 2,000 users of a scheme known as Liberty may not be recoverable, the Labour MP said, because in 30 cases HMRC failed to start inquiries into personal tax returns within the 12 month deadline.
"Although HMRC says Liberty was an exceptional case among the 750,000 personal tax return inquiries each year, it was unable to tell us how much delays had cost across the different tax avoidance schemes," she said.
Liberty was an investment scheme deliberately designed to avoid tax, and reportedly used by celebrities including singer Katie Melua, George Michael and Gary Barlow.
It was said to have helped shelter £1.2bn from the Treasury.
The committee members were also concerned about slow progress in acting on information from the Falciani list, which identified 3,600 UK individuals potentially avoiding tax using Swiss bank accounts.
They called on HMRC to use the new powers granted by parliament to tackle tax avoidance and report on its progress.
The MPs also said that Revenue & Customs failed to properly tackle companies that took advantage of international tax structures to reduce their UK liabilities.
"Some international tax experts believe that the UK's tests for companies to gain tax residency are less rigorous than in other EU jurisdictions.
"Research into seven companies who have recently relocated to the UK for tax purposes showed very little inward investment was generated or jobs created in the UK in return for the tax benefits the companies receive," Mrs Hodge said.
"HM Treasury and HMRC should provide the committee with details of progress in identifying and addressing the ways that international tax structures are exploited, and set out the actual costs and benefits of recent changes to the UK's tax regime."
In December 2013, the MPs accused HMRC of "losing its nerve" when mounting tax prosecutions against multinational corporations.
The committee also highlighted the £1.9bn error made by the tax authorities when setting a baseline for its compliance work. The mistake went undetected for three years.