General rule
(a) The time and place of examination pursuant to the provisions of section 1862 of this title shall be such time and place as may be fixed by the Director and as are reasonable under the circumstances. In the case of a summons under authority of paragraph (2) of section 1862 of this title the date fixed for appearance before the Director shall not be less than 10 days from the date of the summons.
Restrictions on examination of taxpayer
(b) No taxpayer shall be subjected to unnecessary examination or investigations, and only one inspection of a taxpayer's books of account shall be made for each taxable year unless the taxpayer requests otherwise or unless the Director, after investigation, notifies the taxpayer in writing that an additional inspection is necessary.