The five year Tax Cap has not worked according to Douglas West MHK.
The initiative introduced in February was designed to attract wealthy people to the Island.
Chris Thomas claims the number of individuals paying the tax cap amount of £120,000 has fallen by one sixth in the last year.
There are currently 58 people who have elected for the cap, and only one of those moved to the Island this tax year.
Mr Thomas says the shortfall of contributors means most of the income tax is being supported by general tax payers: