The Social Security and Treasury departments have finished a two-year review of the tax system in the island.
Deputy Gavin St Pier said the review found anomalies in the way the island treats certain incomes for certain ages.
He said: "There are many people who are self employed who would say they are already paying too much."
The review, which started in 2013 looked at ways to incentivise people to work and support themselves.
It also examined how to ensure the tax system was competitive with other areas and States expenditure is controlled.
Deputy St Pier said: "If you are self employed your tax and social insurance burden is 30.5% up to the upper earnings limit of Â£132,000.
"One thing the survey has identified is that some of those anomalies, particularly in the way we treat certain incomes for certain ages and how social insurance is attached to those incomes, is something that needs to be looked at."
He said the departments plan to publish their findings in February for debate by the States in March.
Some people in Guernsey may be paying too much tax, according to the treasury minister.