Final answer:
Legislative regulations have the highest tax validity as they are issued by Congress and carry the force of law, unlike procedural, interpretive, or temporary regulations. c. Legislative
Step-by-step explanation:
When it comes to types of tax regulations, the one with the highest level of authority and tax validity is legislative regulations. Legislative regulations are issued by Congress and have the force of law behind them. They are definitive legal standards that taxpayers must comply with.
On the other hand, procedural regulations deal with the administration and enforcement of tax laws, not with the content of the law itself. Interpretive regulations are issued by the Treasury Department to provide guidance on the interpretation of the law, but they do not have the same legal weight as legislative regulations.
Temporary regulations are issued to provide immediate guidance on new legislation but are expected to be replaced with final regulations, and thus also lack the enduring authority of legislative regulations.