Kinds of tax exemptions
There are three (3) kinds of tax exemptions: [1] express; [2] implied; and [3] contractual.
They are express when the law expressly grants it to a person or persons. They are implied when a person or persons are excluded in enumeration or not covered by the scope of the taxing provisions of the law. They are contractual when the State descents to the level of an individual and enters into an agreement for a person or persons to perform an obligation in exchange of tax exemption.
The third kind (contractual), if valid, cannot be revoked by the State unilaterally.
They are express when the law expressly grants it to a person or persons. They are implied when a person or persons are excluded in enumeration or not covered by the scope of the taxing provisions of the law. They are contractual when the State descents to the level of an individual and enters into an agreement for a person or persons to perform an obligation in exchange of tax exemption.
The third kind (contractual), if valid, cannot be revoked by the State unilaterally.