Where the numbers come from
The BAS report does not read a separate "GST register". It walks your general ledger for the BAS period and groups every line by its tax code. Each box on the BAS is derived from the journals that posted during the quarter (or month, if you lodge monthly).
- G1 — Total sales (including GST): gross customer invoices with tax codes for GST on sales, GST-free sales, Export sales and Input-taxed sales. The figure is GST-inclusive.
- 1A — GST on sales: the 10% GST portion of customer invoices coded GST on sales. GST-free, export and input-taxed sales contribute zero to 1A.
- G10 — Capital purchases (including GST): bills and expenses against asset accounts (the fixed-asset register flows in here automatically).
- G11 — Non-capital purchases (including GST): every other deductible bill / expense, GST-inclusive.
- 1B — GST on purchases: the 10% GST portion you can claim back on G10 + G11.
- W2 — PAYG withholding: pulled from your payroll runs against the PAYG withheld liability account.
Cash vs accrual basis
The top of the BAS page has a basis toggle.
- Accrual: GST is recognised on the invoice issue date and the bill received date. This is how most businesses report.
- Cash: GST is recognised on the payment received date and the bill paid date. Eligible if your annual turnover is under $10 million and you have elected cash accounting with the ATO.
Switching the toggle re-runs the calculation against the same period. The number you see on screen is the number that will print on the lodgement summary.
What does not appear on the BAS
- Wages and super payments are not GST-bearing and are excluded.
- Bank fees coded GST-free contribute to G14 only (not 1B).
- Internal transfers between two of your own accounts net to zero — they appear nowhere.
Common surprises
If a customer invoice was coded Standard but a line item had its tax overridden to $0, that invoice will appear in G1 but not in 1A. The GST Audit Report flags this exact pattern — run it before lodgement, fix any anomalies, then re-open the BAS report. The numbers update live.