Certain Montana drunk driving penalties apply not only when you get convicted in a dui or dwi case but also when you refuse to take the chemical test at the time of dui stop. Refusal to taking the chemical test is treated as a separate offence and attracts separate penalty regardless of the fact whether you get convicted or not. For the first time refusal, your license will be suspended for six months, and for subsequent refusal, the license will be suspended for one year and installation of ignition interlock device (not mandatory but very much likely) will be required at your own expense.