Montana's DUI penalties depend on three things: how many prior convictions count, which kind of DUI you are convicted of, and whether a passenger under 16 was in the vehicle. The charts below put every combination in one place, and each row names the subsection it comes from. This page is part of our Montana DUI Guide.
How to Read the Chart
- Impairment DUI means a conviction under MCA § 61-8-1002(1)(a): driving while your ability to operate a vehicle safely was diminished.
- Per se DUI means a conviction under § 61-8-1002(1)(b), (c), (d), or (f): an alcohol concentration of 0.08 (0.04 in a commercial vehicle), THC of 5 ng/mL, or a listed drug level.
- Aggravated DUI means a DUI plus one of the facts in MCA § 61-8-1001(1), such as an alcohol concentration of 0.16 or more. Our aggravated DUI page lists all four.
The offense number is not always the number of arrests you have had. A prior counts toward a second offense only if it falls within 10 years, and every prior counts once you reach a third (MCA § 61-8-1011(1)(b)). Our second and third DUI page explains how priors are counted.
First, Second, and Third Offense: Jail and Fines
| Offense and charge | Jail | Fine | MCA |
|---|---|---|---|
| First, impairment DUI | 24 consecutive hours to 6 months | $600 to $1,000 | § 61-8-1007(1)(a)(i) |
| First, per se DUI | Up to 6 months, no minimum | $600 to $1,000 | § 61-8-1007(2)(a)(i) |
| First, aggravated DUI | 2 days to 1 year | $1,000 | § 61-8-1007(4)(a)(i) |
| Second, impairment DUI | 7 days to 1 year | $1,200 to $2,000 | § 61-8-1007(1)(a)(ii) |
| Second, per se DUI | 5 days to 1 year | $1,200 to $2,000 | § 61-8-1007(2)(a)(ii) |
| Second, aggravated DUI | 15 days to 1 year | $2,500 | § 61-8-1007(4)(a)(ii) |
| Third, impairment DUI | 30 days to 1 year | $2,500 to $5,000 | § 61-8-1007(1)(a)(iii) |
| Third, per se DUI | 30 days to 1 year | $2,500 to $5,000 | § 61-8-1007(2)(a)(iii) |
| Third, aggravated DUI | 40 consecutive days to 1 year | $5,000 | § 61-8-1007(4)(a)(iii) |
Where the chart says "consecutive," the statute uses that word. Where a minimum exists, it may not be suspended or served on home arrest unless the judge finds that jail would pose a risk to the person's physical or mental well-being (MCA § 61-8-1007(1)(d), (2)(d), (4)(b)). Our page on mandatory jail time explains what that means in practice.
With a Passenger Under 16
| Offense and charge | Jail | Fine | MCA |
|---|---|---|---|
| First, impairment DUI | 48 consecutive hours to 1 year | $1,200 to $2,000 | § 61-8-1007(1)(a)(i) |
| First, per se DUI | Up to 6 months, no minimum | $1,200 to $2,000 | § 61-8-1007(2)(a)(i) |
| First, aggravated DUI | 4 consecutive days to 1 year | $2,000 | § 61-8-1007(4)(a)(i) |
| Second, impairment DUI | 14 days to 1 year | $2,400 to $4,000 | § 61-8-1007(1)(a)(ii) |
| Second, per se DUI | 10 days to 1 year | $2,400 to $4,000 | § 61-8-1007(2)(a)(ii) |
| Second, aggravated DUI | 45 days to 1 year | $5,000 | § 61-8-1007(4)(a)(ii) |
| Third, impairment DUI | 60 days to 1 year | $5,000 to $10,000 | § 61-8-1007(1)(a)(iii) |
| Third, per se DUI | 60 days to 1 year | $5,000 to $10,000 | § 61-8-1007(2)(a)(iii) |
| Third, aggravated DUI | 90 consecutive days to 1 year | $10,000 | § 61-8-1007(4)(a)(iii) |
These are still misdemeanors. A separate felony, criminal child endangerment, can be charged in some cases with a child under 14. See DUI with a crash or a child in the car.
Fourth and Later Offenses: Felony DUI
| Tier | Custody | Fine | MCA |
|---|---|---|---|
| First felony DUI, corrections option | 13 months to 2 years with the Department of Corrections, then a 5-year prison term that must be suspended | $5,000 to $10,000 | § 61-8-1008(1)(a)(i) |
| First felony DUI, treatment court option | Up to 5 years in a treatment court program, with required completion | $5,000 to $10,000 | § 61-8-1008(1)(a)(ii) |
| Felony DUI after an earlier felony DUI sentence | State prison for up to 10 years | $5,000 to $10,000 | § 61-8-1008(2) |
| After a sentence under the 10-year tier | State prison for up to 25 years | $5,000 to $10,000 | § 61-8-1008(3) |
| After a sentence under the 25-year tier | State prison for 5 to 25 years; the first 5 years may not be suspended | $5,000 to $10,000 | § 61-8-1008(4) |
The felony statute does not have separate aggravated or child-passenger rows. Which tier applies turns on how a person was sentenced before, so it has to be read from the record. Our guide to the felony DUI treatment program goes further.
License, Treatment, and Vehicle Consequences
| Conviction | License | Treatment and vehicle | MCA |
|---|---|---|---|
| First conviction | 6-month suspension | Assessment and education course. The court may attach testing or an interlock to a probationary license. | §§ 61-5-208(2)(b)(i), 61-8-1009(1)(a), 61-8-1010(1) |
| Second conviction (prior within 10 years) | 1-year suspension. No probationary license until 45 days are served and the court recommends one. | Assessment and treatment. The court must order testing, an interlock restriction, or vehicle forfeiture. | §§ 61-5-208(2)(b)(ii), 61-8-1009(1)(b), 61-8-1010(2) |
| Third conviction | 1-year suspension. No probationary license until 90 days are served and the court recommends one. | Same as a second conviction. | §§ 61-5-208(2)(b)(iii), 61-8-1009(1)(b), 61-8-1010(2) |
The suspension runs from the date of conviction (MCA § 61-5-208(3)(a)). On a second or third conviction, it stays in effect past the year if required treatment is not finished (§ 61-5-208(2)(b)). A felony DUI conviction brings at least a 1-year loss of the license and a notation of probation restrictions on any license issued afterward (§ 61-5-208(6)). A test refusal has its own, separate suspension, covered on our license suspension page.
What the Chart Leaves Out
- Surcharges and costs. Courts add set surcharges to every fine. See DUI fines and surcharges.
- The suspended portion. Jail above the minimum may be suspended for up to 1 year on conditions (MCA § 61-8-1007(1)(e)). That period works like probation.
- No deferred sentence. A court may not defer imposition of sentence for a DUI (MCA § 61-8-1011(4)).
- A prior or pending aggravated DUI. It moves a later ordinary DUI into the aggravated rows (MCA § 61-8-1007(1)(c), (2)(c)).
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.