Article 159 provides a clear prohibition on private agreements regarding tax liability. It stipulates that a taxpayer is legally forbidden from entering into an agreement to transfer their tax burden to another person. This means that for the purposes of Omani law, the statutory taxpayer remains solely responsible for the tax due, regardless of any private contractual indemnity or shifting of cost. This prevents parties from obfuscating the legal source of tax payments and ensures that the Tax Authority's recourse against the primary liable party is never contractually diminished.