Chancellor Rachel Reeves is considering changes to the tax system which would lead to some lawyers, accountants and doctors paying more, in next month's Budget.
The professions are among those which sometimes use limited liability partnerships (LLPs), meaning they are treated as self-employed and not subject to employers' National Insurance.
The Times reported that Reeves would impose a new charge on people using LLPs, which would be slightly lower than the 15% rate of employers' National Insurance.
Reeves is widely expected to raise taxes in her Budget on 26 November, after gloomy economic forecasts and a series of U-turns on welfare cuts made it harder for her to meet her own fiscal rules.
