624. Power to inquire into personal and trustees' returns.

An officer of Revenue and Customs1 may inquire into a return2 if he gives notice of his intention to do so ('notice of inquiry') to the person whose return it is ('the taxpayer'), within the time allowed, that is to say:

  1.  

    (1)     if the return was delivered on or before the filing date3, up to the end of the period of 12 months after the day on which the return was delivered;

  2.  

    (2)     if the return was delivered after the filing date, up to and including the quarter day4 next following the first anniversary of the day on which