Free tool

Work-Use Expense Calculator

For an expense used for both work and personal reasons, this works out the work-related portion from the total and a work-use percentage, and shows what is left. It is arithmetic, and decides nothing for you.

A$

The total you paid, including GST if it applied.

60%

The share of the expense that relates to your work.

Work-related portion

A$72.00

Total expense
A$120.00
Remainder (not work-related)
A$48.00

Across a year

If this expense repeats, the yearly figures are shown below.

If charged monthly
A$864.00
If charged weekly
A$3,744.00

This is arithmetic, not advice. It does not decide whether an expense is deductible, which method applies to you, or what percentage is reasonable in your circumstances. That depends on current ATO rules and your own situation, and a registered tax agent is the person to ask.

Where the percentage comes from

From a basis you can explain, such as hours, calls or jobs counted over a few representative weeks, written down with the expense. The guide sets out how to measure it and keep it consistent.

A car is different. Its work share comes from cents per kilometre for the trips you record, or from a logbook kept for at least twelve weeks, not from an estimate. HeyJerni's Drive records each trip by GPS and keeps that logbook.

How to separate work and personal expenses

Frequently asked questions

What is a work-use percentage?

It is the share of a mixed expense that relates to your work. A phone bill used partly for work is normally recorded as a percentage of the bill rather than as a whole work expense.

Does this tell me what I can claim?

No. It multiplies an amount by a percentage. Whether the expense is deductible at all, and what percentage is reasonable, depends on your circumstances and current ATO rules.

Do I still need the receipt?

Yes. The percentage describes how the expense was used. The receipt or bill is the evidence that the expense happened at all.

Can HeyJerni store this for me?

Yes. Each expense in the app carries a purpose and a work-use percentage, and the receipt image stays attached to the same record.

Related pages

Sources

Last reviewed: September 2026. Tax information on this page is based on publicly available Australian Taxation Office guidance. HeyJerni is a record-keeping tool and does not provide tax or financial advice.

Record the percentage where the receipt is

HeyJerni keeps the amount, the work-use percentage and the receipt image on the same record, and exports the lot at 30 June.

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