The Court of Tax Appeals in Mirant (Philippines) Operations Corp. v. CIR, CTA Case No. 6382 (7 June 2005) confirmed that the filing of an application for tax treaty relief with the Bureau of Internal Revenue, and the subsequent issuance of an official ruling to confirm the application of a preferential tax rate under a Philippines treaty, are mandatory for the non-resident taxpayer who intends to avail of such a preferential rate on its Philippine-source income. The non-resident taxpayer cannot rely on rulings issued to other taxpayers, who may not actually be similarly situated, as basis for treaty relief