Card spending gets tracked almost by accident — it's sitting in a banking app whether you log it or not. Cash doesn't have that safety net. A float in the ute, cash handed over for a few hours' labouring, change from the hardware counter — it all gets spent on the job and none of it leaves a paper trail unless you make one.
What "petty cash" actually covers on a tradie's job
- A working float — cash kept on hand for small, immediate job costs.
- Cash paid to a helper — a few hours of labouring paid cash, which may still need recording as a business expense.
- Parking and tolls — rarely card-only, almost never logged.
- Small hardware counter buys — a box of screws, a tube of sealant, paid in cash because it's quicker.
- Tips and odd cash-in — cash a client hands over on the day, which still needs recording as assessable income.
None of it is large on its own. Across a job, it's routinely $80–$200 that never makes it into any record at all.
Why a cash tin and a notebook don't survive contact with a real job
The plan always starts well: write it in the notebook as it happens. By week two the notebook's under a tarp in the ute, half the entries are guessed from memory, and the float total never matches what's in the tin. It's not a discipline problem — paper cash books were never built for someone with dirty hands standing in the heat.
What a petty cash app actually needs to do
- Log cash the same way as receipts — one feed, not two systems to reconcile later.
- Tag every cash entry to a job — cash spent on one job shouldn't blur into another's totals.
- Track a running float balance — so you know what's left without counting the tin.
- Work without a card or bank feed — cash has no transaction to import, so entry needs to be genuinely fast.
- Capture GST where it applies — even a cash purchase from a GST-registered supplier can carry a valid tax invoice worth claiming.
- Export cleanly — a bookkeeper needs cash in and cash out just as clearly as card spending.
| Method | What actually happens |
|---|---|
| Cash tin, no log | Float slowly drains with no record of where it went. |
| Paper cash book | Accurate for a week, abandoned once the pages get lost. |
| Spreadsheet | Needs typing up later, so cash entries get forgotten before they're recorded. |
| App with cash entries (like Site Wallet) | Logged in seconds on-site, tagged to the job, rolled into the same total as receipts. |
A worked example
Say you start a job with a $200 float. Through the week: $30 for parking across a few site visits, $80 cash to a helper for a day's work, $25 at the hardware counter for fixings, and $10 in odds and ends. Logged against the job as it happens, that's $145 of tracked job cost — and $55 left in the float, matching what's actually there. Without logging it, you'd only know the float's gone, not where.
How Site Wallet handles it
Cash entries sit in the exact same feed as scanned receipts — add an amount, tag the job, done in a few seconds. Every entry rolls into the job's running total alongside card spending and receipts, so a job's true cost includes cash the moment it's spent, not weeks later from memory. Come tax or BAS time, cash and card exports sit side by side, so nothing gets left out of the records the ATO expects.
FAQ
Do I need a receipt for every small cash purchase?
Where you can get one, keep it — a cash purchase from a GST-registered supplier can still carry a valid tax invoice worth claiming a GST credit on. For small spends without one, a logged entry with the date, amount and purpose is far better than nothing.
Does cash paid to a helper need to be reported?
Yes — it's still a business expense and, depending on the arrangement, may carry its own reporting obligations. Check with your accountant based on how the person is engaged.
Is cash a client hands me still assessable income?
Yes — cash income is treated the same as any other income for tax purposes and should be logged and declared just like a bank transfer or card payment.