First: Will It Apply to You?
An interlock is a breath tester wired into your car's ignition. You blow into it, and if there's alcohol in your breath, the car won't start. Queensland doesn't give a magistrate a choice about this. If your charge is on the list, the condition goes onto your licence automatically when you get it back — it isn't part of your sentence and it isn't something you can argue against in court.
Whether it applies to you comes down to the exact charge on your court paperwork, not the number on the breath test alone:
| Driving under the influence — the charge used at 0.150 and above, or where you were affected regardless of the reading | Yes, first time |
|---|---|
| A reading of 0.100 to 0.149 — over the middle limit but not the high limit | Yes, first time |
| Refusing or failing to provide a breath or blood specimen | Yes, first time |
| Dangerous driving causing death or serious injury, with alcohol as an aggravating feature | Yes |
| A reading of 0.050 to 0.099 — over the general limit but under 0.100 | Only if you have a qualifying drink driving conviction in the last 5 years |
| Any alcohol at all on a learner, P-plate or provisional licence, while unlicensed, in a truck or bus, or on a restricted licence | Only if you have a qualifying conviction in the last 5 years |
That distinction between 0.099 and 0.100 is worth sitting with, because it is the whole difference between walking away at the end of your disqualification and paying for a device in your car for a year. It also means the reading itself is worth checking properly. If the analysis is arguable, or if the reading can be challenged down below 0.100, the consequence is not just a smaller fine — it's no interlock at all.
One more thing that catches people out: if you already have an interlock requirement from another state and you move here, it follows you across the border and applies to your Queensland licence.
What It Means Day to Day
Once your disqualification ends and you reapply, your new licence carries an interlock condition. From that point, you nominate one specific vehicle to the Department of Transport and Main Roads, have an approved interlock fitted to it at your own cost, and that is the only vehicle you may drive. Not your partner's car, not a mate's ute, not a work vehicle — unless it's been nominated and fitted too.
There are only two exceptions. You can drive the vehicle supplied by an accredited driver trainer while you're having a lesson in it, and you can drive any vehicle while sitting a practical driving test. Nothing else.
If there's only one car in the household and someone else needs to drive it as well, that can be arranged — a vehicle can be nominated for more than one person. The device either has to identify each driver by PIN or swipe card, or every nominated driver has to keep a written log of who was driving and when. Using someone else's PIN, or letting someone use yours, is a separate offence, and so is failing to keep the log properly.
How Long Will You Have It?
For most people who do the right thing, 12 months. That 12 months is time spent holding a valid licence and either driving only your fitted, nominated vehicle or holding an exemption. It does not have to be 12 months in a row — if you stop driving for a while, or your licence lapses, that time simply doesn't count towards it. Nothing in the Act sends you back to zero.
You will see a five-year figure mentioned in relation to the scheme. That's an outer limit on how long the condition can hang over you, not a target. It only becomes relevant if the 12 compliant months take years to accumulate. There's one exception: if you're a repeat offender who has to complete a repeat offender education program, the condition keeps running until you've done it or been excused from it.
A new drink driving conviction while the condition is running doesn't extend it. It cancels your licence, and you start the whole process again on the back of the new disqualification.
What Makes the 12 Months Longer
Two things can add time. The first is automatic and the one that hurts most.
An alcohol reading, or a missed service, in the last four months. If the interlock records a breath sample with alcohol in it during the final four months, or locks out permanently because you missed a required service appointment, your end date is pushed out to four months after that event. There's no hearing. You get a letter telling you it's happened.
The practical effect is that the last four months are the ones to be careful in. A blow at 8am after a big night, in a car you were only going to move up the driveway, can cost you four more months of rental fees.
There is a right of review, and the grounds are realistic ones: someone else blew into the device, the device wasn't working properly, or your service was done but wasn't recorded correctly. If you're sure you didn't do what the data says you did, that's worth acting on quickly rather than accepting the letter.
A show cause notice, adding four months. Separately, the department can propose adding four months if you drove the car without providing a sample yourself, drove it knowing the interlock wasn't working, or drove it knowing it had been tampered with. You get at least 28 days to put your side of it before a decision is made — that is a real opportunity, not a formality.
If You Live a Long Way From an Installer
This is the part that matters most in Far North Queensland, because the interlock scheme was designed for people who live near a fitting workshop and can drop the car in for servicing without losing a day.
You can apply to be exempted from having an interlock fitted at all. The grounds that actually exist are:
- You live outside a 150km radius of the nearest approved installer's place of business, and outside any area where that installer runs a mobile fitting service. Both parts have to be true.
- You live on a Queensland island with no installer on it and no bridge connection to the mainland. A list of larger islands is excluded from this ground.
- A medical condition, backed by a doctor's certificate, that stops you providing a strong enough breath sample to work the device.
- It isn't physically possible to fit an interlock to the only vehicle you can realistically drive, and refusing the exemption would cause severe hardship to you or a family member with no other transport available.
- A family member has a medical condition preventing them using the device, there's only one car available, and there's no other transport.
- Other severe hardship — but specifically not hardship in the form of being unable to drive to work or to study. Those two are carved out.
Two warnings on this. Being unable to afford the device is not, by itself, severe hardship — that's spelled out in the regulation. And the distance ground is a fixed 150km radius test, not an argument about how inconvenient the drive is; 140km of bad road will not get you there.
You can't lodge the application until six weeks before your disqualification ends, or the day a restricted licence order is made if you were granted one. It has a fee. The department has 28 days to decide, and if it doesn't, the application is treated as refused — although a real decision made after that overrides the deemed refusal. If you're granted an exemption it can come with its own conditions, and breaching those is an offence in itself.
What It Costs
Every cent of it is yours to pay. There's an installation fee, a monthly rental and monitoring fee for as long as the condition runs, servicing appointments through the term, and a removal fee at the end. These are set by the approved interlock providers, not by the court, and they're on top of any fine.
Before you assume you'll just wear it, get the current fitting and monthly fees from an approved provider and multiply the monthly figure by twelve. For people who barely drive, or who live out of town and would burn a day travelling for each service, the exemption application is often the better path — and the two questions are worth deciding together, before you reapply for your licence, rather than after the device is in the car.
The Mistakes That Cost People the Most
- Driving a car that isn't the nominated one. If it has no interlock in it at all, the maximum fine is about $4,800 for a first offence and about $10,400 for a second within five years — and the court must disqualify you again for three months, or six on a repeat. That disqualification puts you straight back to the start of the interlock process. If the car did have an interlock but simply wasn't yours to drive, it's a fine without the extra disqualification.
- Letting someone else blow into it for you. This is the classic route to a four-month extension, and it risks the offence above if you then drive.
- Breaching a condition of your exemption. Same fine range as above, with the same mandatory further disqualification.
- Not telling the department when your circumstances change. If you got an exemption and the facts behind it change — you move closer to town, for instance — you have 14 days to say so, and there's a fine if you don't.
Where We Can Actually Help
Three points in this process are worth a lawyer's involvement. The first is at the charge itself, because whether the reading is 0.099 or 0.100 decides whether any of this happens to you. The second is the exemption application, which is a written case made to the department on prescribed grounds, not a conversation — the difference between a bare form and a properly evidenced application is usually the outcome. The third is a show cause notice or an automatic extension you believe is wrong, where you have a limited window to respond.
Where This Comes From
Transport Operations (Road Use Management) Act 1995 (Qld), Chapter 5 Part 3B (ss 91I–91Z) — The interlock scheme. Section 91I defines which offences it catches; s 91K imposes the condition; ss 91M–91N set the interlock period and the 12-month prescribed period; ss 91P–91T cover exemptions; ss 91U, 91V and 91VA cover extensions; ss 91W–91Y create the offences; s 91Z sets out review rights.
Same Act, ss 79 and 79A — The drink driving offences and the limits that decide which one you're charged with: general 0.050, middle 0.100, high 0.150. A reading of 0.100 to 0.149 is s 79(1F); 0.050 to 0.099 is s 79(2).
Transport Operations (Road Use Management—Driver Licensing) Regulation 2021 (Qld), ss 333–349 — The detail: approved interlock models (s 334), sharing a nominated vehicle (ss 335–340), the 150km radius (s 341), the island, physical-impossibility, family medical and severe hardship exemption grounds (ss 343–346), the rule that affordability alone is not hardship (s 347), and the grounds for reviewing an automatic extension (s 349).
Penalties and Sentences Regulation 2025 (Qld) — A penalty unit is $172.70 from 1 July 2026. The figures above are 28 and 60 penalty units.