When taxpayer denies receipt of the formal letter of demand, it becomes incumbent upon the BIR to overcome the denial.

As main defense against the Warrant of Distraint and/or Levy and collection of an alleged deficiency tax assessment, taxpayer denied having received formal assessment notice. According to the Court, based on Section 228 of the 1997 Tax Code and Section 3 of Revenue Regulations No. 12-99, the issuance of a valid formal assessment is a substantive prerequisite to tax collection. It contains not only a computation of tax liabilities but also a demand for payment within a prescribed period, thereby signaling the time when penalties and interests begin to accrue against the taxpayer and enabling the latter to determine his remedies therefor. Due process requires that it must be served on and received by the taxpayer. When taxpayer denies receipt of the formal letter of demand, it becomes incumbent upon the BIR to overcome the denial. (Southern Entertainment Gallery, Inc. vs. Commissioner of Internal Revenue, CTA Case No. 8257, July 9, 2014)