Your first BAS: what to check before you lodge

1. Check which quarter the invoice belongs in

Start with the dates shown on your business activity statement (BAS) and confirm whether you report GST on a cash or non-cash basis. If this is your first BAS and you registered for GST partway through the quarter, check your registration start date as well. Don’t assume that the dates in a report you ran last month match the dates on your statement.

In our example, the $1,100 invoice includes $100 GST, the whole amount is paid in one go and there’s no deposit. If you report GST on a cash basis, the $100 goes in the October–December quarter, when you receive the payment. On a non-cash basis, it goes in July–September, when you issued the invoice. For non-cash reporting, the general rule is to use the earlier of issuing the invoice or receiving any payment. The ATO guide to GST accounting methods explains both. If the customer paid in instalments or you received a deposit, check the treatment before using this example.

2. Match the payment to the invoice you already raised

Open the invoice in your software and see whether the October payment is linked to it. If you recorded the deposit as a new sale, your records may now show two sales for the same job and an invoice that still looks unpaid. Match the bank deposit to the existing invoice. If the quarter has already been lodged, ask your accountant how to correct it before changing the earlier records.

Then compare the bank and credit card transactions in your software with the actual statements for the period. Check transfers between your own accounts, money you put into the business and loan deposits separately. Those deposits can look like sales in a bank feed, so look at where the money came from before accepting a suggested category.

3. Review supplier invoices, refunds and shared expenses

Supplier invoice: If you bought $330 of materials, a bank entry tells you what you paid, but it doesn’t show whether GST was charged. For purchases costing more than $82.50 including GST, you generally need a valid tax invoice before claiming a GST credit. Ask the supplier for a copy if you only have an EFTPOS slip or a bank entry. Keep the proof of purchase for smaller transactions too.

Supplier refund: If you returned part of that order, keep the credit note or refund paperwork with the original invoice. Match the money coming back into your account to the return. If you already claimed a GST credit on the original purchase, flag it for review: the refund may require a GST adjustment.

Shared phone bill: If your phone bill includes $10 GST and you can support 60% business use, the GST credit would generally be $6, assuming the purchase otherwise qualifies. Keep a note of how you worked out that percentage. The ATO’s GST credit guidance covers purchases used for both work and personal purposes.

4. Make a short list of what still needs checking

Before you lodge or send the figures to your accountant, gather the records below. If something doesn’t make sense, note the date, amount and what you think it was for. “$330 at the supplier, invoice missing” is more useful than a folder of unlabelled screenshots.