Two five year periods apply here and they are not the same five years. Almost every wrong answer on this topic comes from treating them as one.
The two clocks
A logbook is valid for five income years. The year it was kept, plus the four following. That is covered in how long a logbook stays valid.
Records must be kept for five years after you last rely on them. That period starts when the validity period ends, not when it begins.
They run in sequence, not in parallel. The logbook you keep this year may still be supporting a claim in five years, and it then has to be kept for five years after that.
The arithmetic
This part is derived from the two rules rather than stated anywhere as a single figure, so treat it as arithmetic and check the dates against your own circumstances.
Keep a logbook during 2026-27. Rely on it through to 2030-31, the fifth and final year of its validity. The retention period then runs five years from the end of that latest year you relied on it.
The record therefore needs to survive roughly a decade from the twelve weeks you spent creating it. That is a long time for a file to sit on a phone, and it is the practical case for exporting the finished logbook rather than trusting a device to still be around. See where your logbook data lives.
Written evidence of expenses
The logbook establishes the percentage. It says nothing about what the car cost you, and the costs need their own evidence.
Keep written evidence for five years from the date you lodge the return that claims the expense. Source: ATO, keeping records.
Note that the clock starts at lodgment, not at the end of the income year, so lodging late extends the period you have to hold the records.
Three situations run longer than five years:
- you are in dispute with the ATO, in which case you keep records for the later of five years from the date you lodge and five years from the date the dispute is resolved
- you claim a decline in value deduction, where the period runs from the last claim rather than from the year of purchase
- you have acquired or disposed of a capital gains tax asset, where the period runs until five years after it is certain no CGT event can happen
The decline in value case catches car owners specifically. If you are depreciating the vehicle, the purchase records have to survive the entire depreciation period, which can be considerably longer than five years from the year you bought it.
What written evidence has to show
A valid document has to show five things:
- the cost of the expense
- the supplier
- the nature of the goods or services
- the date the expense was paid
- the date the document was produced
A standard tax invoice carries all five. Most receipts do too.
A bank or credit card statement is not written evidence on its own. The ATO’s reason is direct: it is not from the supplier, and it generally does not include all the required information. The $340 at a service centre could be a major service or four new tyres, and the statement cannot tell the difference. A statement is a useful supporting document and a poor primary one.
The $300 threshold does not apply to car expenses
This is worth being blunt about, because it is one of the most expensive misconceptions in the whole area.
There is a $300 substantiation threshold for total work-related expenses, below which written evidence is not required. Car expenses are excluded from it.
There is no small-claim exemption for car expenses. Whichever method you use, you need to be able to substantiate the claim: written evidence of the costs under the logbook method, or a reasonable and demonstrable basis for the kilometres under the cents per kilometre method. A logbook claim of $180 needs the same evidence as one of $8,000.
Format
Records can be kept on paper or electronically, including photographs of written evidence. Copies must be a true and clear copy of the original, and they must be in English where you incurred the expense in Australia. An expense incurred overseas may be documented in that country’s language, though the ATO can ask for a certified translation.
A photograph of a receipt is fine, provided it is legible and the five elements above are readable in it. A photograph where the total is sharp and the supplier is cut off is not evidence of much.
Two practical points that follow from a ten year horizon:
Retrievable means retrievable. A receipt in an app that no longer installs, or a format nothing opens, has not been kept in any meaningful sense. PDF and CSV are safe bets. Proprietary formats are not.
Back it up somewhere that is not the phone. The retention period will outlast the device by several generations.
The practical routine
At the end of a logbook period: export the completed logbook and store it with the year’s tax records. Do not leave it only in the app.
At the end of each income year: record the odometer readings, file the year’s receipts, and note which logbook year you are relying on. Details in what odometer readings you need.
When a logbook expires: do not delete it. It has five more years to run as a record, even though it has stopped being usable as a basis for a claim. That distinction is the entire subject of this page, and it is the one that catches people at exactly the wrong moment.