On October 5, 2016, the Bureau of Internal Revenue (BIR) sent KLM Corp. a Final Assessment Notice (FAN), stating that after its audit pursuant to a Letter of Authority duly issued therefor, KLM Corp....

On October 5, 2016, the Bureau of Internal Revenue (BIR) sent KLM Corp. a Final Assessment Notice
(FAN), stating that after its audit pursuant to a Letter of Authority duly issued therefor, KLM Corp. had
deficiency value-added and withholding taxes. Subsequently, a warrant of distraint and/or levy was
issued against KLM Corp. KLM Corp. opposed the actions of the BIR on the ground that it was not
accorded due process because it did not even receive a Preliminary Assessment Notice (PAN) after
the BIR’s investigation, which the BIR admitted.

a) Distinguish a PAN from a FAN.
b) Are the deficiency tax assessment and warrant of distraint and/or levy issued against KLM
Corp. valid? Explain.