Check your car modifications against the rules in your state. Pick your state and the mods you’ve done or are planning, and for each one you’ll see whether it’s fine as is, needs an inspection or an engineer’s certificate, or isn’t allowed on the road, with a link to the government document the answer comes from.
Car Modification Legality Checker
Pick your state and your mods. See whether each one is fine as is, needs an inspection or an engineer's certificate, or isn't allowed on the road, with the exact government rule behind every answer.
Your paperwork
Plain-text summary for forums
A guide to the published rules, not legal advice or a compliance certificate. Every answer quotes the government document it comes from, but inspectors apply the rules to your actual car, and documents change. Your state road authority or a licensed engineer has the final say: confirm anything you're unsure about with them before you buy parts or drive. Rules verified November 2026.
What car modifications are illegal in Australia?
Most mods are legal somewhere, either within set limits or with an engineer’s sign-off. A short list is banned in every state that addresses it:
- Nitrous oxide systems, including a disconnected system fitted ready for use (VSB 14 Section LA).
- Quick-release or removable steering wheels (VSB 14 Section LS).
- Removing or bypassing the catalytic converter or any other emission control equipment.
- Wheel spacers or adaptors the manufacturer didn’t fit. WA is the one exception: the CEO of the Department of Transport can approve them.
- An exhaust without a silencer that all the gas passes through, or a valved exhaust that can’t be tested fully open.
- Welded or locked diffs and spools (Victoria and Queensland).
Valves that vent to atmosphere are close behind: NSW and Queensland ban blow-off valves that vent to atmosphere, the NT fails wastegates that vent to atmosphere, and South Australia bans aftermarket blow-off valves outright. Everything else depends on where the car is registered, which is why the checker asks for your state first.
Lowering and lift limits by state
Nationally, VSB 14 allows a car to be lowered by up to 50 mm, or a third of its suspension travel, without certification, and raised by 50 mm in total from all sources. Every car must keep at least 100 mm of ground clearance within a metre of an axle. The states then add their own versions.
| State | Lowering without certification | Lift without certification | Beyond that |
|---|---|---|---|
| NSW | The lesser of 50 mm or a third of travel, on factory mounts | 50 mm of suspension, with tyres inside the 7% diameter trigger | VSCCS certificate |
| VIC | 50 mm or a third of travel | 4WDs and goods vehicles: 75 mm (50 suspension, 25 from tyres) with a commercial kit. Cars: 50 mm | VASS certificate |
| QLD | No millimetre limit; keep 100 mm clearance | 4WDs and goods vehicles: 75 mm (50 suspension, 25 from tyres), no body blocks. Cars: 50 mm | Approved Person, up to 150 mm under LS9 |
| WA | Keep at least two thirds of bump travel | 50 mm | Complex modification with CEO approval |
| SA | 50 mm total change | 50 mm total change | LVES report and inspection |
| TAS | A third of travel | 50 mm | LS8 plate up to 150 mm (max 75 mm suspension) |
| ACT | A third of travel (owner certified) | 50 mm | Engineering certificate |
| NT | A third of travel | 75 mm; up to 100 mm with inspector approval | Formal assessment and engineering over 100 mm |
Bigger tyres count towards lift at half their diameter increase, so tyres 50 mm taller add 25 mm. Run your exact sizes through our tyre size calculator to get the figure.
Window tint laws by state
The front side windows must let through at least 35% of light in every state and territory. Behind the driver, the limit and the conditions vary.
| State | Front side windows | Behind the driver | Condition |
|---|---|---|---|
| NSW | 35% | 20% | Two exterior mirrors; 35% with a driver-side mirror only |
| VIC | 35% | 20% | A mirror on each side |
| QLD | 35% | 20% | A mirror on each side; otherwise the rear glass stays at 70% |
| WA | 35% | 20% | ADR 14 mirrors on each side |
| SA | 35% | 20% | None stated |
| TAS | 35% | 20% | A mirror on each side; otherwise the rear glass stays at 70% |
| ACT | 35% | 20% | None stated |
| NT | 35% | 15% | Mirrors on both sides for any tint below 70% |
Windscreens can only carry a band across the top, covering the greater of the area above the wiper sweep or the top 10% of the screen (WA caps it at 10% of the area). Reflectance is capped at 10%. Every figure is the glass and film combined, measured on the car, so 35% film on glass that passes 80% of light ends up at about 28% and fails. The NT’s 15% rear limit exists because of a Registrar’s exemption gazetted in January 2009.
Exhaust, decats and noise limits
An aftermarket exhaust is legal in most states as long as the catalytic converter and the rest of the emission gear stay in place and the car meets its noise limit. The ACT is stricter: its inspection manual only owner-certifies exhausts that were a factory option, so anything else needs an engineering certificate. Removing the cat is illegal everywhere, and in NSW it is an offence under the Clean Air Regulation.
For cars not certified to ADR 83, the stationary noise limit is 90 dB(A) for cars built from 1983 and 96 dB(A) for older ones. Victoria’s cut-off is 1 November 1983 and the ACT’s is 1 January 1982. Cars certified to ADR 83, phased in between 2005 and 2007, are allowed no more than 5 dB(A) above the stationary level set when they were certified. In NSW the fine rises with how far over the limit the car is, and Victoria bans temporary noise defeat devices such as removable baffles.
ECU tunes, blow-off valves and engine swaps
This is where the states disagree most. Queensland allows a remap without approval if the car still meets its emission standards and power rises by no more than 20%. NSW needs a licensed certifier for any reflash. South Australia doesn’t allow recalibrating the ECU on an original engine at all. Victoria needs a VASS certificate for any change that significantly increases performance or affects emissions on cars built from 1986. In the NT, a Transport Inspector can approve it as a basic modification.
Adding a turbo or supercharger needs certification in every state except the NT, where it is also a basic modification. A manufacturer’s optional engine is generally fine; anything else needs certification. NSW draws the line at an engine not original to an equivalent vehicle or more than 20% bigger, WA needs the CEO’s approval for anything larger than an optional engine, and the ACT owner-certifies swaps under 15% more capacity from the same engine family.
Headlight conversions, light bars and underglow
LED globes in halogen headlights fail inspection in the NT and Tasmania, and Queensland calls them generally not permissible. NSW only allows them if they are designed as a direct replacement and meet the technical requirements, South Australia wants evidence of ADR approval, and WA treats them as a modification that needs examining. HID kits are banned outright in Tasmania; the NT and South Australia allow them in factory housings with the kit maker’s ADR evidence and certification.
Most states allow up to four extra driving lamps, and a light bar counts as one if all its LEDs work together. They must only come on with high beam, and Queensland, WA, South Australia and Tasmania don’t allow them on top of a bull bar. Underglow is legal in WA if it doesn’t flash and other drivers can’t see the lights themselves, and in the ACT if it causes no glare or confusion. Victoria, Queensland and Tasmania ban it. Smoked or tinted light lenses are banned in Victoria, Tasmania, the ACT and the NT.
Seats, harnesses and steering wheels
Aftermarket front seats need certification in NSW (unless they are ADR compliant for an equivalent vehicle), Victoria, Queensland, Tasmania and the ACT. South Australia needs no application if they are installed to VSB 5, and in the NT a Transport Inspector approves them. Harnesses need certification in NSW, Queensland and the ACT.
An aftermarket steering wheel marked to ADR 10 and at least 330 mm across is fine in most states, though WA needs an inspection and a permit. Quick-release hubs are banned everywhere. No state offers a standard way to remove a steering wheel airbag: South Australia bans it, and the ACT and NT fail any car with an inoperative airbag.
Engineer’s certificates: what each state calls them
| State | Certificate | Issued by | Worth knowing |
|---|---|---|---|
| NSW | VSCCS compliance certificate | Licensed certifier | Interstate certificates are not recognised |
| VIC | VASS Approval Certificate | VASS signatory | Tell VicRoads within 7 days if the engine number changes |
| QLD | Modification certificate and plate | TMR Approved Person | May not be recognised in another state |
| WA | Modification permit, or engineering certification and VSS approval | Authorised Inspection Station, or a DoT-approved Automotive Consultant | Regulation 235 lists alterations that need the CEO’s approval |
| SA | LVES report with an application to modify | Light Vehicle Engineering Signatory | Engine replacements are notified to Service SA |
| TAS | Approved modification plate | Certification under VSB 14 | Certified mods without a plate fail inspection |
| ACT | Engineering certificate | Authorised engineering signatory | Owner certified mods need no inspection or reporting |
| NT | Modification certificate or plate | Transport Inspector, or the Technical Advisory Committee for significant mods | No application fee |
Sources
Every rule in the checker comes from these documents, checked in November 2026.
- Australian Light Vehicle Standards Rules 2015 (national model rules)
- Vehicle Standards Bulletin 14, Sections LA, LK and LS
- Transport for NSW VSI 06 Light vehicle modifications (Rev 4, July 2026) and VSI 64 Aftermarket forward facing lamps
- NSW Protection of the Environment Operations (Noise Control) Regulation 2017
- VicRoads VSI 8 Guide to modification for motor vehicles, with VSI 2, VSI 12 and VSI 19
- Victoria Environment Protection Regulations 2021
- Queensland TMR Vehicle Standards Information: Minor Modifications, and Driving Lamps including LED Light Bars
- Queensland Code of Practice: Vehicle Modifications, Code LS9
- WA Road Traffic (Vehicles) Regulations 2014
- WA Department of Transport information bulletins IB-108, IB-119, IB-132 and IB-134
- SA Modification of Light Vehicles fact sheet (MR1457)
- Tasmania Light Vehicle Inspection Manual, Reasons for Rejection (V23)
- ACT Inspection Manual for Light Vehicles
- NT information bulletins V15, V32(lv), V51 and the NT Light Vehicle Inspection Manual
This page and the checker are a guide to the published rules, not legal advice or a compliance certificate. Inspectors apply the rules to your actual car and documents change, so confirm anything you’re unsure about with your state road authority or a licensed engineer before you buy parts.
FAQ
A handful are banned in every state that addresses them: nitrous oxide systems (even disconnected), quick-release or removable steering wheels, removing or bypassing the catalytic converter, and exhausts without a silencer. Wheel spacers are banned everywhere except WA, where the CEO of the Department of Transport can approve them. Most other mods are legal within limits or with an engineer’s certificate, and the limits change from state to state.
Yes, within limits. Most states allow up to 50 mm, or a third of the suspension travel, without certification, as long as the car keeps at least 100 mm of ground clearance near the axles. Go further and you need certification in NSW, Victoria, WA, SA, Tasmania and the ACT. Queensland sets no millimetre limit, only the 100 mm clearance rule.
It depends on the state. Queensland allows a remap without approval if the car still meets its emission standards and power rises by no more than 20%. NSW needs a licensed certifier for any reflash. South Australia doesn’t allow recalibrating the ECU on an original engine. In the NT, a Transport Inspector can approve it as a basic modification.
35% on the front side windows in every state and territory. Behind the driver it’s 20% in most places and 15% in the NT, but several states only allow that with mirrors on both sides. In Queensland and Tasmania a car with only a driver-side mirror can’t have rear tint below 70%. The figure is glass and film combined, so 35% film ends up darker than 35% on the car.
Only in WA and the ACT, and only with conditions. WA allows underbody lights that don’t flash and can’t be seen directly by other drivers; the ACT allows them if they don’t cause glare or confusion. Victoria, Queensland and Tasmania ban them, and NSW, SA and the NT publish no permission for them.
Yes, everywhere. In NSW it’s an offence to drive a car with an impaired anti-pollution device, WA’s regulations require every emission control system to stay fitted, and the inspection rules in Victoria, SA, Tasmania, the ACT and the NT fail a car with the cat removed.
A VSCCS compliance certificate in NSW, a VASS Approval Certificate in Victoria, an Approved Person modification certificate in Queensland, an LVES report in SA, and a modification plate in Tasmania. WA and the NT also have a middle tier, where an inspector approves simpler mods without an engineer.
Not always without redoing the paperwork. NSW does not recognise certificates issued under another state’s scheme, Queensland warns its certificates may not be recognised elsewhere, and the NT tells owners to check with the new state before moving.
