All appeals are dismissed.

The costs of appeal are assessed against the plaintiffs.

The grounds of appeal are examined.

As a matter of principle, the tax by the method of tax return is determined by the taxpayer's own determination of the tax base and the amount of tax, and the payment is determined by the specific tax liability determined by the return, and the State and local governments hold the tax amount paid based on the finalized tax claim.

Unless a taxpayer's filing of a return is void as a result of significant and apparent defects, it shall not be deemed as unjust enrichment.

Here, whether a defect in the act of reporting constitutes the invalidity of the law because it is significant and clear should be determined reasonably by considering the purpose, meaning, function, and legal remedies for defective act of reporting as a basis for the act of reporting from a teleological perspective, and by individually identifying specific circumstances caused by the act of reporting.

(see, e.g., Supreme Court Decisions 94Da60363, Dec. 5, 1995; 2006Da81257, Apr. 23, 2009). Based on its stated reasoning, the lower court rejected all of the Plaintiffs’ claims on the grounds that the act of return and payment in this case cannot be deemed null and void as a matter of course because it cannot be deemed that there is a serious and obvious defect.

Examining the records in light of the aforementioned legal principles, although the court below’s reasoning was somewhat inappropriate, the conclusion that rejected the Plaintiffs’ assertion is acceptable, and contrary to what is alleged in the grounds of appeal, there were no errors by misapprehending the legal principles on the invalidity of a report.

Therefore, all appeals are dismissed, and the costs of appeal are assessed against the losing party. It is so decided as per Disposition by the assent of all participating Justices on the bench.