People often mix up an IID compliance period with the time an ignition interlock device is simply installed in a vehicle. They are not the same. The installation period is just the calendar span when the device is physically in the car. An IID compliance period is the stretch of time when a driver must not only have the device installed, but also use it correctly and avoid violations such as missed rolling retests, tampering, failed breath samples, or skipped service appointments.

That difference matters because agencies and courts usually care about compliance, not just hardware. A person can have an interlock in the car for months and still fail to complete the required compliance period if the record shows violations. In license cases, that can delay full driving privileges, trigger a new license suspension, or lead to another administrative hearing.

In Michigan, the Secretary of State reviews interlock records in restoration and restricted-license cases. For many drivers seeking full reinstatement after revocation, a common benchmark is at least 12 months of violation-free interlock use, though the exact requirement depends on the order and hearing result. If a crash happens during a noncompliant period, that can complicate an injury claim. Driving outside license restrictions may be used as evidence of poor judgment or negligence, and insurers rarely find that charming.