This is general guidance, not personalised tax advice. Rules and thresholds change — check ato.gov.au or your accountant for your specific circumstances.
Every quarter, the same scene plays out in utes and garages across the country: a glovebox full of faded receipts gets tipped out onto a kitchen table with the BAS deadline two days away. It doesn't have to be like that — the fix isn't more admin, it's the same admin done once, at the point of spending, instead of reconstructed under deadline pressure.
Why job costing and BAS overlap
BAS needs accurate GST collected and GST credits figures for the quarter. Job costing needs the same underlying numbers, broken down by job, tracked as they happen. Log every job cost properly through the quarter and your BAS becomes a rollup of numbers you already have — not a reconstruction exercise against a deadline.
GST on materials and subbies
If you're GST-registered, most materials, plant hire and subcontractor invoices you pay GST on can support a GST credit claim on your BAS — provided you're holding a valid tax invoice for purchases over $82.50 (GST-inclusive). That means every receipt matters, not just the big ones. A pile of unclaimed $40 receipts across a quarter adds up to real GST credits left on the table.
What BAS actually requires
- Total sales and GST collected on those sales for the period
- Total business purchases and GST credits claimed on them
- PAYG instalments, if applicable to your situation
- PAYG withholding, if you employ staff
Job-level tracking through the quarter feeds directly into this — every tagged receipt is a GST credit already categorised and ready, rather than something to sort through at the last minute.
PAYG instalments
If you're required to pay PAYG instalments, these are prepayments toward your expected annual tax bill, generally based on your last return or current income. Keeping accurate, up-to-date job costing through the year makes it far easier to judge whether your instalment rate still matches reality — rather than getting a nasty surprise at tax time.
A simple quarterly routine
- Scan every receipt the day it happens — don't let them pile up in the ute.
- Tag each one to the job it belongs to.
- Weekly, check each open job's running cost against its quote.
- Monthly, reconcile the running total against your bank and card statements.
- At BAS time, export everything in one go for your bookkeeper or yourself.
FAQ
What if I've already lost receipts from earlier in the quarter?
Bank and card statements can help estimate missing spend, but the ATO prefers original tax invoices, especially for GST credit claims. Going forward, capturing receipts digitally the moment you get them avoids the problem entirely.
Do cash payments to a subbie need to be recorded for BAS?
Yes — cash payments for legitimate business costs still need recording, and depending on the arrangement, PAYG withholding or contractor reporting obligations may apply.
Does job-level tracking actually help with BAS, or just with quoting?
Both — the same tagged receipts that show you a job's real margin are exactly the records that make a BAS lodgement fast and defensible if the ATO ever asks questions.