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Ignition interlock requirements, costs and approved companies in every state

An independent guide for drivers ordered to install an ignition interlock. Pick your state to see who has to install one and for how long, what it costs for the whole order, and which companies are approved, with every fact linked to the law it came from.

IIHS · October 2026 Shading shows whether an interlock is required after a first DUI conviction. Your own court order or DMV letter is what applies to you.

Who installs them

Each state keeps its own list of approved interlock companies, and you have to use one on your state's list. We read 44 of those lists and counted how many each company appears on.

  1. Smart Start40/44
  2. Intoxalock37/44
  3. LifeSafer34/44
  4. Alcohol Detection Systems28/44
  5. RoadGuard28/44
  6. Low Cost Interlock19/44
  7. Guardian16/44
  8. ALCOLOCK12/44
  9. Sens-O-Lock7/44

Out of the 44 state lists we could read. See how they rank

Guides

All 11 guides
What is an ignition interlock device?How the device works, what installation involves, who needs one and what it costs.What an interlock costs for your whole orderLease, install, calibration and removal added up, plus the fees that aren't advertised.Best ignition interlock companies in 2026Eight companies ranked on state approvals, fee transparency and published device detail, with the scoring shown.Cheapest ignition interlock: 12-month costs comparedWhat a year costs at each company from filed fee schedules, and the programs that cut the bill.Interlock violations and what happens nextWhat the device logs, who sees it, and how states treat a missed retest compared with a failed one.Getting the interlock removedWho signs off in each state, the paperwork, and the removal fee.

Ignition interlock laws by state

Full guides for 22 states so far, with the rest in review. Every state page has the IIHS rule, the agency that runs the program and its sources.

Data table and CSV

Swatch: IIHS first-offense rule (October 2026). ● full guide.

How we check the numbers

Laws

For each state we read the statute and the agency's own page, quote both next to the fact, and date the check.

Prices

We record what each company advertises and the fee schedules they file with New York State, with the date of each.

Approvals

Company lists come from the state agency that approves devices, so a company's own claims about where it operates don't count.

InterlockCompare doesn't make, sell or install interlocks. Some companies may pay us when you book through a link here. Tables are sorted by the data shown in them, and payment doesn't move anyone up. How we make money