The Liberal Democrats have announced plans to introduce a new criminal offence of corporate failure to prevent tax evasion.
The proposals would see firms which help people dodge tax hit with the same penalty as the individual evading tax. It is not clear whether the policy would extend to financial advisers.
The party has also promised to strengthen codes of practice for professions advising on tax affairs.
Chief secretary to the Treasury Danny Alexander says: “The overwhelming majority of people who pay their taxes have every right to expect that everyone else does the same. A tiny minority still behave as if tax evasion is more akin to a sport than a crime.
“It is a crime, plain and simple. If someone helps a break-in to your home they end up in the dock as an accomplice. It should be the same if some helps a tax evader.”
The Lib Dems have also committed to reducing the tax gap in each year of the next parliament.
In 2012/13, the amount of tax that HM Revenue & Customs believed was owed totalled around £500bn. Of that, £466bn was collected, leaving a tax gap of £34bn.
The plans come as the Labour Party has also pledged to introduce a new bill to target tax dodgers as one of the first acts of a Labour treasury.