Commissioner of Internal Revenue v. Systems Technology Institute, Inc.

Summary

The Commissioner of Internal Revenue assessed Systems Technology Institute, Inc. for deficiency income tax, VAT, and expanded withholding tax totaling P161.8 million for fiscal year 2003. STI executed three waivers extending the assessment period, but challenged the assessments on grounds of prescription. The Court of Tax Appeals found the waivers defective for non-compliance with BIR regulations, specifically lacking notarized written authority for the signatory, failing to specify tax types and amounts, and some assessments already being prescribed when the first waiver took effect. The Supreme Court affirmed, ruling that waiver requirements must be strictly followed, and STI was not estopped from raising prescription despite requesting reinvestigation. The case reinforces that defective waivers cannot extend tax assessment periods, and the BIR cannot rely on estoppel to cure procedural defects it caused.