This legal analysis examines a documented inconsistency in the allocation and legal classification of an immovable property tax payment by a Latvian municipal authority. Based on official tax notices, payment data and successive written replies issued in August 2026, the study reconstructs the allocation of a EUR 63.71 payment and analyses a residual EUR 4.96 liability attributed by the authority to two different due dates. The analysis addresses the legal consequences of this inconsistency under Latvian administrative and tax law, including the requirements of legal certainty, reason-giving, transparent payment allocation and the lawful calculation of late-payment interest. The documentary record demonstrates that the EUR 4.96 balance can be mathematically reconstructed as a remainder connected with the instalment due on 15 May 2026, while a subsequent official explanation associates the same amount with entries carrying a due date of 16 November 2026. Because the applicable due date determines whether a liability is overdue and whether late-payment consequences may arise, the discrepancy requires an official, auditable reconciliation. The paper is published as an independent legal and documentary analysis for public research, transparency and rule-of-law purposes.