A sur-tax is an additional tax that is imposed on top of an existing tax. There are multiple synonyms for sur-taxes, such as supplementary taxes, extra taxes, additional taxes, and special taxes. These taxes are levied by governments to raise revenue for various purposes like infrastructure development, healthcare, education, and welfare programs. Some other synonyms that can be used in place of sur-taxes include top-up taxes, additional levies, excess taxes, and premium taxes. Though sur-taxes might be a burden on taxpayers, they are necessary to fund public services and government programs and help in achieving socio-economic development.