[1] This rule is related to the Flora full payment rule, based in part on the United States Supreme Court decision in Flora v. United States,[2] essentially requiring that in most cases a person resisting the assessment of a U.S. federal tax must first pay the full amount of tax asserted by the Internal Revenue Service (IRS) and then file a formal administrative claim for refund with the IRS.
As a general rule, the courts will not entertain a suit to enjoin (or stop) the government from assessing the tax but will entertain a suit for a tax refund after the IRS has denied the refund claim, or 6 months have elapsed (120 days in bankruptcy cases) since the filing of the claim, whichever is earlier.
[4] In the case of National Federation of Independent Business v. Sebelius, in which the constitutionality of the Patient Protection and Affordable Care Act was at issue, the U.S. Supreme Court upheld the constitutionality of the mandate imposed under that law.
The Court also determined the applicability of the Tax Anti-Injunction Act to the litigation over the law.
In this case, the mandate was ruled to be constitutional as a valid exercise of the congressional taxing power.