(1) An employer must file Form MW-3 with applicable federal Form W-2s and submit payment within 30 days after ceasing to be an employer, as defined in 15-30-2501, MCA, or ceasing activity. Ceasing activity includes, but is not limited to:
(a) quits doing business;
(b) sells or transfers the business, or the major portion of the business assets; or
(c) becomes insolvent.
(2) If the report and payment are not received within 30 days, the accrued taxes are subject to penalty and interest as provided in 15-1-216, MCA.