Section 45B. With respect to declarations of estimated tax and estimated tax payments required under the provisions of chapters sixty-two B and sixty-three B, the commissioner may, by regulation, provide that such declarations be filed and estimated tax payments be made to a bank designated as a depositary and fiscal agent under section forty-five. The use of a bank for this purpose shall not be considered a violation of the provisions of section twenty-one; provided, however, that all employees of said bank having access to declarations or documents to which section twenty-one is applicable shall be subject to the provisions of said section twenty-one, including the penalties for their violation under subsection (c) of said section twenty-one.