Claiming work-related car expenses is one of the most common tax deductions in Australia but it’s also one of the most misunderstood. Many taxpayers assume that once they’ve completed a logbook, they’re covered for five years without needing to revisit it.
However, according to guidance from the Australian Taxation Office (ATO), this assumption can lead to incorrect claims, audit risk, or missed deductions if your circumstances change.
This guide explains how motor vehicle logbooks work, when you need a new one, and how to stay compliant while maximising your tax position.
What Is a Motor Vehicle Log Book and Why It Matters
A motor vehicle logbook is a record of your work-related and private travel over a continuous 12-week period. It is used to determine the business-use percentage of your vehicle, which is then applied to calculate your deductible car expenses.
The ATO allows you to rely on a valid logbook for up to five years, provided your usage pattern remains consistent. However, the key requirement is that the logbook must accurately reflect your current work-related travel.
If your circumstances change and your logbook is no longer representative, continuing to use it may result in over-claiming or under-claiming deductions.
When You Must Start a New Log Book (ATO Requirements)
Although a logbook can remain valid for five years, the ATO requires a new one if there are material changes to your circumstances.
You should start a new logbook if:
- You change jobs or job roles
- You move house or change your primary workplace
- Your work-related travel patterns significantly increase or decrease
- Your duties change, requiring more or less driving
These changes affect your business-use percentage, which directly impacts your claim. Using an outdated logbook in these situations may not satisfy ATO requirements.
Using Multiple Vehicles: Log Book Rules Explained
If you use more than one vehicle for work purposes, the ATO requires separate logbooks for each vehicle.
Each logbook must:
- Cover the same 12-week period
- Accurately reflect the usage of that specific vehicle
This ensures consistency and prevents discrepancies when calculating deductions across multiple cars.
Buying a New Car: Can You Use Your Old Log Book?
If you purchase a new vehicle, you may still be able to rely on your previous logbook—but only under specific conditions.
The ATO requires you to:
- Ensure your usage pattern remains substantially the same
- Make a written nomination confirming that the old logbook is still representative
- Complete this before lodging your tax return
If your usage has changed, you will need to complete a new 12-week logbook for the new vehicle.
Log Book vs Cents Per Kilometre Method: Key Differences
The ATO provides two main methods for claiming car expenses:
Log Book Method
- Based on actual expenses (fuel, insurance, depreciation, etc.)
- Requires a valid logbook
- Typically results in larger deductions for high work-related use
Cents Per Kilometre Method
- Fixed rate per kilometre (set annually by the ATO)
- Simpler, but limited to a maximum number of kilometres
- No logbook required, but you must be able to justify your estimate
Choosing the right method depends on your usage and record-keeping habits.
Employer-Provided Vehicles and Novated Leases: What You Can’t Claim
A common mistake is attempting to claim deductions on a vehicle that you do not own.
If your car is:
- Provided by your employer, or
- Salary packaged through a novated lease
you generally cannot claim work-related car expenses under either the logbook or cents per kilometre method.
This is because the costs are typically already covered through employer arrangements or salary packaging benefits.
Electric Vehicles (EVs) and Hybrid Cars: ATO Guidelines
The ATO has introduced specific guidance for electric vehicles (EVs) and plug-in hybrids, particularly regarding home charging costs.
Electric Vehicles
- You can use the ATO’s home charging rate (e.g. 4.2 cents per km, increasing to 5.47 cents for 2026–27)
- This provides a simplified method based on odometer readings
- If you use this rate, you cannot separately claim commercial charging costs
Plug-in Hybrid Vehicles
- A different calculation method applies
- You must apportion electricity costs using an ATO-approved formula
These rules highlight the importance of choosing the correct method and maintaining supporting records.
Record-Keeping Requirements: Staying ATO Compliant
To support your claims, the ATO requires accurate and complete records, including:
- A valid 12-week logbook
- Odometer readings at the start and end of each financial year
- Receipts for car expenses (if using the logbook method)
- Evidence of work-related travel
Failure to maintain proper records can result in denied deductions or penalties.
Common Mistakes to Avoid with Log Books
Many taxpayers fall into avoidable traps when claiming car expenses. These include:
- Using an outdated logbook that no longer reflects actual usage
- Failing to start a new logbook after a job or lifestyle change
- Claiming expenses on employer-provided vehicles
- Overestimating work-related travel without supporting evidence
Avoiding these mistakes is essential to ensuring your claims are both accurate and defensible.
Key Takeaways: Getting Your Log Book Right
Motor vehicle logbooks remain one of the most effective ways to maximise tax deductions—but only when used correctly.
To stay compliant and optimise your claim:
Ensure your logbook reflects your current usage patterns
Start a new logbook when circumstances change
Maintain accurate and complete records
Seek professional advice if unsure about your eligibility
Conclusion: Stay Accurate, Stay Compliant, Maximise Deductions
ATO scrutiny around work-related expenses continues to increase, and motor vehicle claims are a key focus area. While the logbook method can deliver significant tax benefits, it also requires discipline and accuracy.
If your work, travel patterns, or vehicle arrangements have changed, now is the time to review your logbook. A small update today could prevent costly mistakes at tax time—and ensure you’re claiming exactly what you’re entitled to.
Source: ATO
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