How long is an interlock required?
An ignition interlock is a breath tester wired to your car: the engine starts only after you pass it. How long you must keep it depends on your state, on whether you have had a DUI (a drunk driving conviction) before and, in some states, on your blood alcohol level. For a first DUI, most states on this list require 6 months to a year, and a second or later DUI means longer. Find your state, then see when your time starts and what can make it longer.
Required interlock time by state
Every state sets its own rule, so the same DUI can mean very different times in different states. The table shows the shortest time each state asks for. You only need the row for your state. If your state isn't here, see our table of all states.
Some times depend on your BAC, short for blood alcohol content: how much alcohol your breath or blood test showed when you were stopped. A BAC of 0.08 means 0.08 percent of your blood is alcohol. That is the legal limit for driving in most states, so 0.15 is almost twice the limit. Your BAC is on your arrest paperwork.
| State | First DUI | Second DUI | Third or later |
|---|---|---|---|
| Alabama | 6 months, or 1 year in a serious case | 1 year | 3 years, or 5 years for a 4th DUI or later |
| Alaska | 6 months | 12 months | 18 months |
| Arizona | 12 months, or 18 if your BAC was 0.20 or more | 12 months, or 24 if your BAC was 0.20 or more | 24 months |
| California | Up to 6 months, if a judge orders it | 1 year, or 2 years if someone was hurt | 2 years, or 3 years if someone was hurt |
| Colorado | 9 months, or 2 years if your BAC was 0.15 or more | 2 years | 2 years |
| Connecticut | 1 year | 3 years, if it came within 10 years of the first | Your license is taken away. If you get it back, you need an interlock |
| Florida | 6 months, if a judge orders it, your BAC was 0.15 or more, or a child was in the car | 1 year, or 2 years if your BAC was 0.15 or more | 2 years |
| Massachusetts | Not needed | 2 years | 2 years |
| New Jersey | 3 to 15 months, longer for a higher BAC | 2 to 4 years after your license comes back | 2 to 4 years after your license comes back |
| New York | 12 months | 12 months | 12 months |
| Pennsylvania | 1 year, or none if your BAC was only a little over the limit | 1 year or 18 months, by how long you lost your license | 1 year or 18 months, by how long you lost your license |
| Virginia | 12 months | 12 months, on every car you own | 12 months, on every car you own |
| Washington | 1 year | 5 years | 10 years |
In Alabama, a serious case means a BAC of 0.15 or more, a child 14 or under in the car, or someone hurt.
In New York, a judge can allow less than the usual 12 months. Colorado's 9-month rule for a first DUI applies if you were arrested on or after January 1, 2023.
When does the clock start?
Your time usually doesn't start on the day of your arrest. Often your license is suspended first, which means it is taken away for a set time. In Connecticut, a first DUI means 45 days without a license. The 1 year with the device starts after that.
Pennsylvania counts its 1 year from the day you get your license back. In Arizona, two things must happen before the year starts. You must be allowed to have your license back, and you must have the letter saying a court found you guilty.
What can make your time longer?
If you pass your tests and keep every service visit (a check-up at the installer's shop to make sure the device still reads your breath correctly), your time ends on schedule. A violation can push the end date back. A violation is anything the device records as breaking the rules: a failed breath test, a skipped retest (when the device asks you to blow again while you drive) or a missed service visit.
What a violation can add in some states:
- Colorado: if the device finds alcohol in 3 different months within one year, you can get up to 1 more year.
- Massachusetts: if you have any violations when you ask to take the device off, you keep it for 6 more months after the last one.
- Washington: the last months before the device comes off must have no violations. If you break a rule then, that count starts again from that day.
- Arizona: service visits are due every 90 days. Missing one suspends your license and starts your time over.
Being convicted of driving a car without the device also adds time: an extra year in Arizona, and 12 months in Pennsylvania for a first DUI.
What a longer period costs
You rent the device, so each extra month is one more payment. That is why the length of time decides most of what you pay. MADD (Mothers Against Drunk Driving) puts installation at about $70 to $150 and the monthly fee at $60 to $80. Added up, that is about:
- 6 months: $430 to $630
- 1 year: $790 to $1,110
- 2 years, the least Colorado and Massachusetts require for a second or later DUI: $1,510 to $2,070
- 3 years, Connecticut's time for a second DUI: $2,230 to $3,030
Keeping every service visit and avoiding violations near the end saves you from paying for extra months.
Where these figures come from: each state's motor vehicle office, the laws cited on our state pages, the National Conference of State Legislatures (a group that tracks state laws) and a report for Connecticut's lawmakers.