Missouri ignition interlock & DWI (DUI) requirements
Missouri requires an ignition interlock after a first DUI only at a BAC of 0.15 or higher (6 months minimum from the date of license reinstatement); below that threshold it is not automatic, though other circumstances set by the statute can still require one. A repeat offense carries 6 months minimum from the date of license reinstatement.
In Missouri the offense is called DWI, driving while intoxicated; this page uses the statute's term. Ignition interlock device rules, approved vendors, SR-22 insurance filing, and license reinstatement in Missouri, cited to the statute and Missouri Department of Revenue, Driver License Bureau.
- IID on first offense
- High-BAC only
- Minimum IID period (first)
- 6 months
- SR-22 filing
- Required · 2 years
The short answers
Do I need an interlock?
- First offense
- Required only above a high-BAC threshold
- Threshold
- BAC 0.15
- Minimum period
- 6 months
What the source says (2)
- First offense
“in which the person's blood alcohol content was found to be fifteen-hundredths of one percent or more by weight of alcohol in such person's blood ... shall not operate any motor vehicle unless that vehicle is equipped with a functioning, certified ignition interlock device”
- Minimum period
“that the person must use for a period of not less than six months from the date of reinstatement of the person's driver's license.”
What it costs here
- State reinstatement fee
- $45
- State fee cap
- Persons with an income at or below 150 percent of the federal poverty level who provide…
- Interlock lease, national range
- $50–$150 per month
What the source says (2)
- State reinstatement fee
“$45 reinstatement fee”
- State fee cap
How to drive legally now
- Restricted license
- Available after a first offense · Restricted Driving Privilege
- Waiting period
- No waiting period
- Hearing-request deadline
- 15 days from the notice
- Driving after a DWI in Missouri: the restricted license
- How to get a license back in Missouri
- Date the hearing deadline with the timeline calculator
What the source says (3)
- Restricted license
“If you have had a prior alcohol-related offense within the past 5 years, you are not eligible for a Restricted Driving Privilege (RDP).”
- Waiting period
“If a person otherwise subject to the provisions of this subdivision files proof of installation with the department of revenue that any vehicle that he or she operates is equipped with a functioning, certified ignition interlock device, there shall be no period of suspension.”
- Hearing-request deadline
“Hearing Information: You may request a hearing to contest the basis for your suspension or revocation. If you want a hearing, you must make your request within 15 days of the date of this notice.”
Approved interlock providers
Vendors listed here appear on the Missouri licensing agency's approved-device list. Listing order is alphabetical and is not a ranking or endorsement. Installation locations are on each vendor's own locator.
Where to get it installed — the official approved-installer list: Agency approved-vendor list
| Vendor | Website | Location finder |
|---|---|---|
| Alcohol Detection Systemslisted by the agency as “Alcohol Detection Systems (ADS)” | Alcohol Detection Systems website | Find a location |
| Intoxalock | Intoxalock website | Find a location |
| LifeSafer | LifeSafer website | Find a location |
| Low Cost Interlock | Low Cost Interlock website | Find a location |
| RoadGuard Interlocklisted by the agency as “RoadGuard” | RoadGuard Interlock website | Find a location |
| Smart Start | Smart Start website | Find a location |
What Missouri law requires
Missouri's ignition interlock, SR-22, and reinstatement rules are set by the statute and agency rules cited below. The values in the tables on this page are taken from those sources and are not interpretations of how they apply to any particular case.
Primary source: Mo. Rev. Stat. § 302.440
Ignition interlock requirement
| Item | Missouri rule |
|---|---|
| IID on first offense | Required only above a high-BAC threshold |
| Minimum IID period, first offense | 6 months minimum from the date of license reinstatement (when required) |
| Minimum IID period, repeat offense | 6 months minimum from the date of license reinstatement (court may impose a longer period) |
Under RSMo § 302.440 a court MAY require an ignition interlock device for any first intoxication-related traffic offense, and SHALL require it when the person's blood alcohol content was 0.15% or more, or the person caused property damage or personal injury, or for a second or subsequent offense. The Department of Revenue states that for first-time offenders an IID is required upon conviction if BAC is at or greater than .150 or if there is personal injury or property damage.
What the source says (5)
- IID on first offense
“in which the person's blood alcohol content was found to be fifteen-hundredths of one percent or more by weight of alcohol in such person's blood ... shall not operate any motor vehicle unless that vehicle is equipped with a functioning, certified ignition interlock device”
- Minimum IID period, first offense
“that the person must use for a period of not less than six months from the date of reinstatement of the person's driver's license.”
- Minimum IID period, repeat offense
“NOTE: In addition to the IID requirements explained above, a court may impose other requirements, such as an IID period longer than six months.”
- Ignition interlock statute
“302.440. Devices, use of, when. — In addition to any other provisions of law, a court may require that any person who is found guilty of a first intoxication-related traffic offense”
- IID on first offense
“if your driving record shows more than one alcohol- or drug-related enforcement contact, or for first time offenders, upon conviction, if BAC is at or greater than .150 or if there is personal injury or property damage”
Removal: Compliance-based with manufacturer certification to the Department of Revenue. The DOR states the IID must be maintained for a minimum of six months from the reinstatement date and the driver is monitored during… Full rule and source
SR-22 requirement
An SR-22 is a certificate an insurer files with the state to confirm that a driver carries the liability coverage the state requires. Some states use an FR-44 or a different form for alcohol-related offenses; where Missouri does, the sources below say so.
| SR-22 filing required after a DUI | Yes |
|---|---|
| Filing period | 2 years |
SR-22 form. The Department of Revenue requires filing and maintaining proof of liability insurance (SR-22) for two years from the starting date of the suspension or revocation. The DOR reinstatement page notes SR-22 is not required for a first-time Administrative Alcohol suspension of a driver under age 21.
What the source says (3)
- SR-22 filing required after a DUI
“File and maintain proof of liability insurance (SR-22 form) for two years from the starting date of your suspension or revocation”
- Filing period
“You need to file the SR-22 form for two (2) years from the starting date of your suspension or revocation.”
- SR-22 requirement
“File and maintain proof of liability insurance (SR-22 form) for two years from the starting date of your suspension or revocation”
Program costs
Fees set by the state are cited to the fee schedule. Vendor charges vary by vendor and are shown as published ranges with the month they were checked.
| Item | Amount | As of |
|---|---|---|
| License reinstatement fee | $45 | 2026-08-29 |
| Reinstatement feeAdministrative Alcohol, alcohol-related moving violation (DWI/BAC), refusal, Abuse & Lose | $45 | 2026-08 |
| Reinstatement fee after re-suspension for failing to maintain a required IID | $20 | 2026-08 |
| IID device pricing | MoDOT states it does not keep a pricing list; costs vary among the ignition interlock companies | 2026-08 |
What the source says (1)
- License reinstatement fee
“$45 reinstatement fee”
Exemptions and special cases
Four questions readers ask once an interlock is ordered — motorcycles, employer vehicles, medical inability to give a breath sample, and reduced-cost programs — answered as Missouri's interlock program page or statute states them.
| Question | Missouri rule |
|---|---|
| Motorcycles | Not addressed on the official pages read RSMo § 302.440 requires that the person 'shall not operate any motor vehicle unless that vehicle is equipped with a functioning, certified ignition interlock device'; neither the statute, the DOR Ignition Interlock Device FAQ, the MoDOT Ignition Interlock page nor 7 CSR 60-2 mentions motorcycles. |
| Employer-owned vehicle | Exempt with conditions Under RSMo § 302.441 a person required to have an interlock may apply to the court for an 'employment exemption variance' to drive an employer-owned vehicle not equipped with a device for employment purposes only. The exemption is not granted to a person who is self-employed or who wholly or partially owns or controls the entity that owns the vehicle, and the person may not drive an employer-owned vehicle used for transporting children under 18 or vulnerable persons, or an employer-owned vehicle for personal use. MoDOT's FAQ states that Missouri law does not require employers to install devices on company vehicles and that, absent a device, the employee cannot drive company vehicles. What the source says“may apply to the court for an employment exemption variance to allow him or her to drive an employer-owned vehicle not equipped with an ignition interlock device for employment purposes only. Such exemption shall not be granted to a person who is self-employed” |
| Unable to provide a breath sample | Not addressed on the official pages read RSMo §§ 302.440-302.462, the DOR Ignition Interlock Device FAQ, the MoDOT Ignition Interlock page and 7 CSR 60-2 (device certification standards) do not provide a waiver or alternative for a person physically unable to provide a breath sample. |
| Reduced-cost / indigent program | Available — Discounted fee schedule Under RSMo § 302.304(18), effective August 28, 2026, a certified ignition interlock device provider must adopt a discounted fee schedule for the payment of device costs by offenders with an income at or below 150 percent of the federal poverty level. A person at or below that level who provides income verification is responsible for ten percent of the cost of the ignition interlock device; additional costs accrued for noncompliance with program requirements are not discounted and are the person's sole responsibility. The provider verifies income from the previous year's federal income tax return, the previous three months of weekly or monthly income statements, or a court order declaring the person's income at or below that level. The statute does not state who bears the remaining cost, and no Department of Revenue or MoDOT page describes an application process. What the source says“A certified ignition interlock device provider shall adopt a discounted fee schedule that provides for the payment of the costs of the certified ignition interlock device by offenders with an income at or below one hundred” |
| Fine may be reduced by device cost | If a court imposes a fine and requires an interlock for the same offense, the fine may be reduced by the cost of the device. What the source says“If a court imposes a fine and requires the use of an ignition interlock device for the same offense, the amount of the fine may be reduced by the cost of the ignition interlock device.” |
| Employment exemption variance - excluded vehicles and uses | A person granted the variance may not operate an employer-owned vehicle used for transporting children under 18 or vulnerable persons, or an employer-owned vehicle for personal use. What the source says“shall not drive, operate, or be in physical control of an employer-owned vehicle used for transporting children under eighteen years of age or vulnerable persons, as defined in section 630.005, or an employer-owned vehicle for personal use.” |
| MoDOT FAQ on employer vehicles | MoDOT states that employers are not required to install devices on company vehicles and that an employee cannot drive company vehicles without a device installed. What the source says“Missouri law does not require employers to install ignition interlock devices on company vehicles for their employees. However, the employee cannot drive company vehicles without an ignition interlock device installed and therefore will need to make other arrangements.” |
| Out-of-state residents | MoDOT states that Missouri law applies to individuals who live in another state if they have received two or more intoxication-related offenses in Missouri, and that they must meet the same requirements as Missouri residents using a device approved for use in Missouri. What the source says“Missouri law applies to individuals who live in another state if they have received two or more intoxication-related offenses in Missouri. Ignition interlock programs vary across the United States. The individual must meet all of the same requirements as Missouri residents.” |
| Renting, leasing or lending a vehicle to a restricted person | RSMo § 577.600 makes it a class A misdemeanor to knowingly rent, lease or lend a vehicle to a person required to use an interlock on all vehicles operated unless the vehicle has a functioning, certified device. What the source says“knowingly rents, leases, or lends a vehicle to a person required to use an ignition interlock device on all vehicles operated by the person unless the vehicle being rented, leased, or loaned is equipped with a functioning, certified ignition interlock device.” |
| Ten-percent share and income verification under the discounted fee schedule (RSMo § 302.304(18)) | A person with an income at or below 150 percent of the federal poverty level who provides income verification is responsible for ten percent of the cost of the ignition interlock device. Costs accrued for noncompliance with program requirements are not subject to discounted rates. The certified provider verifies income from the previous year's federal income tax return, the previous three months of weekly or monthly income statements, or a court order declaring the person's income at or below that level. What the source says“who provides income verification shall be responsible for ten percent of the cost of the ignition interlock device.” |
Compare: motorcycles by state · employer, medical and reduced-cost exemptions by state
Frequently asked questions
- When does Missouri law require an ignition interlock device after a DWI?
- Under RSMo § 302.440, a court may require an IID for a first intoxication-related traffic offense and must require it for a second or subsequent offense, or for any offense in which the person's blood alcohol content was 0.15% or more or the person caused property damage or personal injury. The device must be used for not less than six months from the date the driver's license is reinstated.
- How long must the interlock stay on the vehicle in Missouri?
- RSMo § 302.440 sets a period of not less than six months from the date of reinstatement. The Department of Revenue states the device must be maintained for a minimum of six months from the reinstatement date, with monitoring during the last three months; violations extend the requirement until a three-consecutive-month violation-free period is completed. A court may impose a longer IID period.
- Does Missouri require an SR-22 after an alcohol-related suspension?
- The Department of Revenue's reinstatement requirements state that a driver must file and maintain proof of liability insurance (SR-22 form) for two years from the starting date of the suspension or revocation. The DOR notes SR-22 is not required for a first-time Administrative Alcohol suspension of a driver under 21.
- What is the reinstatement fee for an alcohol-related suspension in Missouri?
- The Department of Revenue lists a $45 reinstatement fee for Administrative Alcohol, alcohol-related moving violation (DWI, BAC), refusal, and Abuse & Lose actions. Reinstatement after a re-suspension for failing to maintain a required IID carries a $20 fee, per the DOR ignition interlock page.
- Who certifies ignition interlock devices in Missouri?
- The Department of Revenue states the IID must be certified and approved by the Missouri Department of Transportation (MoDOT). MoDOT's ignition interlock page lists the approved manufacturers and devices, which must meet the standards in 7 CSR 60-2.
Sources
Record history
- — Record verified against primary sources.