Section 3003. Content of tax due, deficiency, and other notices

Any first
  letter of proposed deficiency or determination (commonly called a thirty
  day  letter)  issued  by  the  commissioner,  and any notice and demand,
  notice of deficiency or notice of determination which is issued  by  the
  commissioner,  which  is  manually initiated and which is the first such
  letter or notice issued to the taxpayer  with  respect  to  the  subject
  matter  of  such  notice,  shall  describe  the  basis  for (such as the
  statutory or  regulatory  law,  or  judicial  or  tax  appeals  tribunal
  decision),  and  identify  the  amounts  (if  any)  of the tax due.   An
  inadequate description under this  section  shall  not  invalidate  such
  letter or notice.