Tax reduction for foreign companies and non residents in mineral oil operations prescribes special tax and surcharge calculation methods. Special reduced income tax applies to a foreign company or specified non resident participating in prospecting, extraction or production of mineral oils: if total income consists only of such profits, tax is computed by applying a reduced rate to that income plus a surcharge on the income tax; if total income includes such profits and other income, tax equals the tax and surcharge on the mineral oil profits under the reduced rate plus income tax on the remaining income at the average rate that would have applied absent the reduced rate provision.