Mr. X is a business man engaged in the importation of crystals from various countries around the world. He sells his crystals online but is actually carrying on his business without the proper SEC registration and business permits from the government. Because of this, the BIR initiated an audit investigation and filed a tax evasion case against Mr. X for his malicious misdeclaration of his taxes for the taxable years 2019-2020. Mr. X did not participate with the BIR and remained silent all through the audit investigation. One day, he received a letter from the BIR and when he opened it, it contained the Final Letter of Demand which already became final and executory and the BIR is informing him that they will be garnishing his bank accounts for that reason. Mr. X now questions the validity of the assessment saying that the whole assessment process was a nullity because he did not receive any Letter of Authority at the first place. Is Mr. X correct? Why or why not. Explain fully and concisely.