Defect does not affect validity

—(1) A notice of assessment or other notice or document issued under this Act shall not be considered invalid or ineffective by reason of a failure to comply with the requirements of section 14, if the taxpayer had effective knowledge of the fact of the notice and of its content. (2) A notice of assessment or other notice or document issued under this Act shall not be considered invalid or ineffective by reason of defect if– (a) it is in conformity in substance and effect with this Act; and (b) the person assessed, or affected by the document, is designated in it according to common understanding.