Texas ignition interlock law

When does Texas require an ignition interlock?

At three points, and they are set by three different statutes. Bond on a repeat charge is Code of Criminal Procedure art. 17.441. Community supervision is art. 42A.408. An occupational license during a suspension is Transportation Code § 521.246.

The bond one surprises people, because it lands before anyone has been convicted of anything. Article 17.441(a) requires a magistrate to order, on release, that a defendant charged with a subsequent offense under § 49.04, 49.05, 49.06 or 49.061, or with an offense under § 49.045, 49.07 or 49.08, have installed on the vehicle they own or most regularly drive a device that uses a deep-lung breath analysis mechanism to make impractical the operation of a motor vehicle if ethyl alcohol is detected in the breath of the operator, and not operate any vehicle without one. Subsection (b) lets the magistrate decline to require it, on the finding that subsection sets out.

On community supervision the statute splits into a discretionary half and a mandatory one. Article 42A.408(b) says the court may require the device of a defendant placed on supervision after a conviction under §§ 49.04–49.08. Subsection (c) says the court shall require it in three cases:

• it is shown at the trial of the offense that an analysis of the defendant’s blood, breath or urine showed an alcohol concentration level of 0.15 or more at the time the analysis was performed;
• the defendant is placed on community supervision after conviction of an offense under §§ 49.04–49.061 for which the defendant is punished under Penal Code § 49.09(a) or (b), which is every second and every third offense; or
• the court determines under subsection (d) that the defendant has one or more previous convictions under §§ 49.04–49.08. Subsection (d) puts a 10-year limit on which of those convictions may be counted for this purpose.

Age is a fourth trigger, in its own subsection. Article 42A.408(e) requires the device of a defendant who was younger than 21 years of age at the time of the offense and was convicted under §§ 49.04–49.08, notwithstanding any other provision of the subchapter or other law. Which of these triggers a case meets follows from how the offense was punished, and that is set out offense by offense in the guide to Texas DWI penalties.

The third route is the license rather than the sentence. Section 521.246(a) requires a judge granting an occupational driver’s license to restrict the person to a vehicle equipped with the device where the person is already under such an order, including one imposed as a condition of bond, or where the license has been suspended, revoked or canceled after a conviction under §§ 49.04–49.08. Subsection (b-1) lets the court waive that only on both of two findings: that the requirement is not necessary for the safety of the community, and that the waiver is in the best interest of justice. What a second offense carries end to end is in the guide to a second DWI in Texas.

How long does the device stay on?

Three answers, because each statute measures it its own way. Supervision counts a percentage of itself, a five-year repeat counts forward from the end of the license suspension, and the occupational license counts the suspension itself.

The supervision figure is a floor rather than a term. Article 42A.408(f) requires the defendant to provide evidence to the court within the 30-day period that the device has been installed on the appropriate vehicle, and to order the device to remain installed for a period the length of which is not less than 50 percent of the supervision period. A two-year supervision therefore carries a minimum of one year of the device, and a judge may set more.

A five-year repeat is measured from the far end instead. Penal Code § 49.09(h) applies to a second or subsequent intoxication offense committed within five years of the date the previous one was committed. It requires the device on each motor vehicle owned or operated by the defendant, obtained at the defendant’s own cost on or before the ending date of the license suspension, and kept installed until the first anniversary of that ending date. Failure to comply with an order under that subsection is punishable by contempt, and the court that entered it keeps jurisdiction until the device is no longer required.

The device is also the condition on driving through a suspension at all. Article 42A.407(g) lets someone whose license is suspended for an offense under §§ 49.04–49.08 operate a vehicle during the suspension where they use the device for the entire period of the suspension and hold an occupational driver’s license with an ignition interlock designation under § 521.2465.

What does an ignition interlock cost per month in Texas?

Published monthly lease prices started at about $90 in August 2026, with installation quoted separately. The statutes set no price at all; they set who pays. The device is leased from a private provider the Department of Public Safety has approved, and the provider sets the rate.

What the providers published: on 19 August 2026, Smart Start listed a Texas monthly lease that “Starts at $89.99+”, installation labor that “Starts at $150.00+” and a calibration fee that “starts at $25.00+”, noting on the page that the figures are as of 1 October 2024 and subject to change. LifeSafer listed Texas rates that “start at under $3 per day” with installation that typically ranges from $50 to $150. Both are starting prices, not quotes.

One monthly figure does come from the statute, and it is not the lease. Article 17.441(d) lets the magistrate designate an agency to verify the installation and monitor the device, and in each month it does either, the defendant pays that agency a reimbursement fee the magistrate sets in an amount not to exceed $10.

All three statutes put the rest of it on the defendant, and only one of them offers terms. Article 42A.408(f) lets a court that finds the defendant unable to pay impose a reasonable payment schedule not to exceed twice the length of the period of the court’s order, and § 521.246(c) lets the court move the cost off the person by entering that finding on the record.

Does the device change when a DWI can be sealed?

On a first DWI placed on community supervision, it moves the date by three years. Government Code § 411.0731(f)(1) allows a petition for an order of nondisclosure on or after the second anniversary of the date of completion of the community supervision, where one condition was met.

That condition is the device, and the subsection is specific about how much of it counts: the person must have successfully complied with a condition of community supervision that, for a period of not less than six months, restricted their operation of a motor vehicle to a motor vehicle equipped with an ignition interlock device. Where the court did not order that condition for that period, subdivision (2) moves the date to the fifth anniversary.

So a condition that reads as a punishment at sentencing is also the shorter of the two routes to a sealed record, and the six months in § 411.0731(f)(1) is well inside the 50 percent art. 42A.408(f) already requires on most supervisions. What sealing does and does not reach, and why a conviction can never be expunged, is in the guide to DWI expungement in Texas.

Eligibility to file is not the same as an order. Section 411.0731(d) has the court issue the order after notice to the state and an opportunity for a hearing, and on its own determination. Nothing on this page can tell you how that goes in your case.

Why does interlock practice vary from county to county?

Because the statutes hand several of the decisions to a local officer by name. The magistrate decides whether to require the device on bond, which agency monitors it, and what the monthly reimbursement fee is; the trial judge decides everything art. 42A.408(b) leaves discretionary.

One of those is written as a county-level figure on the face of the statute. Article 17.441(d) sets the monitoring fee at an amount not to exceed $10 as determined by the county auditor, or by the commissioners court of the county if the county does not have a county auditor, sufficient to cover the cost incurred by the designated agency in that county. Two neighboring counties can run the same statute at two different numbers without either of them departing from it.

Discretion accounts for the rest. Article 17.441(b) is the magistrate’s to exercise, art. 42A.408(b) is the judge’s, § 521.246(b) turns on a finding of good cause, and § 521.246(b-1) turns on a finding about the safety of the community. None of that varies the law; it varies what a courtroom does with it, which is why the county your case is filed in is worth knowing before you read anything general. Our Texas county pages name the courts and the probation department behind an order county by county.

The mandatory triggers do not vary. Article 42A.408(c) uses shall, and a second conviction punished under § 49.09(a) is inside it in every county in the state, along with the 32-hour DWI Intervention class that art. 42A.404 orders alongside it. Send us your order and we will read the program name off it before you pay for a seat.