(a) A return or tax information shall be open to inspection by or disclosure to the attorney general and reporter, and to any of the several district attorneys general, when officially engaged in, and solely for their use in, preparation for any proceeding, or investigation that may result in such a proceeding, before a grand jury or any court of law or equity in a civil or criminal matter involving tax administration, collection or prosecution for violation of the state tax laws, but only if:

(1) The taxpayer is or may be a party to such proceeding;

(2) The treatment of an item reflected on such return is or may be related to the resolution of an issue in the proceeding or investigation; or

(3) Such return or tax information relates or may relate to a transactional relationship between a person who is or may be a party to the proceeding and the taxpayer that affects, or may affect, the resolution of an issue in such proceeding or investigation.

(b) An officer or employee of the department may, in connection with the officer's or employee's official duties relating to an audit, collection activity, or civil or criminal tax investigation or the investigation of any offense or matter under the tax laws of this state, disclose tax information to the extent that such disclosure is necessary in obtaining information, that is not otherwise reasonably available, with respect to the correct determination of tax, liability for tax, or the amount to be collected. Such officer or employee may also disclose tax information when disclosure is required to assure compliance with the tax laws of this state through:

(1) The release of specific tax information; or

(2) Publishing of a bulletin or list identifying persons recognized by the department as qualified sellers, limited users, dealers, and distributors qualified to receive taxable substances, indicating the extent to which they are bonded, or listing similar categories of persons and kinds of data.

(c) Investigative records of the special investigations unit of the department relating to potential criminal prosecutions of persons for violation of the tax laws of this state are confidential and may not be disclosed to any person, notwithstanding any provision of this part to the contrary, except in the exercise of the discretion of the commissioner so as not to seriously impair tax administration.