(1) Pursuant to 49-2-509 , MCA, the department shall issue a notice of dismissal and right to sue at the request of any party to a case before the department if:

(a) the department has completed its investigation of a complaint filed pursuant to 49-2-305 , MCA (housing complaints) ; or

(b) 12 months have elapsed since the complaint was filed.

(2) The department may deny a party's request under (1) for the issuance of a notice of dismissal and right to sue if:

(a) the party requesting the issuance of the notice of dismissal and right to sue has waived the right to request filing in district court either by specific written waiver or by conduct constituting an implied waiver;

(b) the party requesting the issuance of the notice of dismissal and right to sue has filed the request more than 30 days after service of the notice of a hearing (20 days for complaints filed pursuant to 49-2-305 , MCA) , scheduled to be held within 90 days of the date of service of the notice of hearing; or

(c) the party requesting the issuance of a notice of dismissal and right to sue has unsuccessfully attempted through court litigation to prevent the department from investigating the complaint.