Family firms are facing a government clampdown on the practice of income-shifting that could affect up to 300,000 companies.
The practice involves couples who jointly own a company splitting the profits between them in such a way as to minimise their tax exposure.
It has been a target for government legislation ever since HMRC lost the so-called Arctic Systems case in July 2007.
Legislation to outlaw the practice was introduced last month but has been criticised for being too heavy-handed.
"The whole attitude of HMRC and the government has been pretty draconian," said Simon Briault of the Federation of Small Businesses (FSB). "They're trying to make husband-and-wife firms operate on an arms-length basis and keep timesheets."
The FSB and the British Chambers of Commerce are lobbying for the matter to be addressed in the Budget on 12th March.