Which taxes qualify for the protective claim? Estate taxes, income taxes, even gift taxes. In fact, any time you feel you overpaid a tax you can file for a refund, if you have a good reason.
So, what is a protective claim? Any form of taxation is subject to a sort of protective claim. All that is required is that you pay your tax and then file an amended return. It should be filed on the basis of what your return should be if current litigation is decided in that favor.
So, in the event that the outcome of a court decision may change your legal rights with respect to taxes, you may want to consider filing a protective claim. Some may consider it premature, but, in the case of either income taxes or estate taxes, taking the defensive position of a protective claim may be worth it. At the very least, there’s nothing to lose.