Cash vs Accruals: How Your GST Reporting Method Shapes Your BAS

Two ways of accounting for GST

Every business that lodges a BAS has to answer a question that sits quietly underneath every other number on the form: are you reporting GST on a cash basis or an accruals basis? It is one of those pieces of bookkeeping plumbing that rarely gets discussed until something looks wrong — an amount that seems to belong in last quarter's BAS instead of this one, or GST that shows as payable before the money has actually landed in the bank.

Understanding which basis applies to your business, and what it actually changes, is not about doing anything clever. It is about knowing why the timing of the numbers on your BAS sometimes doesn't match the timing of the money moving through your bank account, so you're not caught off guard.

What "cash basis" means in practice

On a cash basis, GST is recognised when money actually changes hands. If you issue an invoice in June but the client doesn't pay until August, the GST on that sale is generally reported in the period the payment was received, not the period the invoice was issued. The same logic applies in reverse for expenses: GST credits are generally claimed in the period you actually paid the supplier, not the period the bill was dated.

This tends to suit sole traders and small businesses well, because it keeps the BAS aligned with what's actually happened in the bank account. You're not reporting GST on income you haven't received yet, which is a meaningful advantage for cash flow — you're not funding the ATO's share of a sale before your customer has paid you.

What "accruals basis" means in practice

On an accruals basis, GST is recognised when the invoice is issued or the bill is received, regardless of when the payment actually clears. Using the same June invoice example: on an accruals basis, the GST on that sale is reported in the period the invoice was raised, even if the customer doesn't pay until two months later.

This method is more common for larger businesses, particularly those with more predictable payment cycles or those required to use accrual accounting for other reporting reasons. It has the advantage of matching income and expenses to the period the work was actually done, which can give a cleaner picture of profitability period to period. The trade-off is that it can create GST obligations ahead of the cash to cover them, which is worth planning around.

An example with an invoice

Say you invoice a client $2,200 including GST on 28 June, and they pay on 15 July.

• On a cash basis, the $200 of GST on that invoice is reported in the BAS period that covers July, because that's when the payment was received.
• On an accruals basis, the same $200 is reported in the BAS period that covers June, because that's when the invoice was issued, regardless of when it was paid.

Neither number is wrong. They're just answering a different question about timing — and the accounting method your business uses determines which one applies to you.

Why this matters for cash flow, not just paperwork

This isn't a purely academic distinction. It shapes when GST actually needs to be set aside. A business on an accruals basis that issues a large invoice near the end of a BAS period may find it owes GST on that sale before the client has paid anything at all. That's a very different cash flow position to a business on a cash basis, which only reports GST once the money is actually in hand.

If you've ever looked at a BAS and wondered why the GST payable seems to be running ahead of what's actually sitting in the business account, the accounting method is often the explanation. It's one of the reasons cash flow forecasting for BAS benefits from knowing, specifically, which basis you're on — the two methods can genuinely produce different BAS outcomes for the same underlying set of transactions.

Timing differences and reconciliation

One of the more common sources of confusion during reconciliation is a transaction that seems to "belong" in a different quarter to the one it appears in. An invoice dated in one BAS period but paid in the next is the classic example. If your records aren't clearly marking which date matters — invoice date or payment date — it's easy to end up double-counting a transaction, or missing it altogether.

This is where consistent record keeping earns its keep. Tracking both the invoice date and the payment date for each transaction, rather than just one or the other, means you can report correctly no matter which basis applies, and you can see clearly why a number appeared in the period it did if you ever need to check back.

Which basis applies to you

Generally, your GST reporting basis depends on factors like your business's turnover, the accounting method you've chosen or been assigned, and how you're registered with the ATO. Some businesses can choose between cash and accruals; others are required to use a particular method based on their circumstances. This isn't something to guess at — the ATO's current guidance at ato.gov.au sets out the eligibility rules, and it's worth checking with a registered tax agent or BAS agent to confirm which basis your business is actually reporting under, since it affects every BAS you lodge from here.

Common points of confusion

A few things tend to trip people up regardless of which basis they're on:

Assuming the invoice date is always what matters. It only is on an accruals basis. On a cash basis, the payment date is what counts, and it's easy to default to invoice-date thinking out of habit.

Mixing the two bases without realising it. If income is tracked one way and expenses another, the BAS can end up internally inconsistent. Being on a single, clearly understood basis for both sides of the ledger keeps things straightforward.

Not revisiting the question as the business grows. A method that made sense at a smaller scale may not still be the most appropriate one once turnover changes or the business's obligations shift. This is a periodic check-in worth having with a tax agent rather than a one-off decision.

Keeping records that work either way

Regardless of which basis applies, the underlying habit that makes BAS time easier is the same: recording both when a transaction was raised and when it was actually settled. Software that tracks income and expenses with both dates visible — rather than collapsing everything into a single date field — makes it much easier to see, at a glance, which BAS period a transaction falls into and why.

It also means that if your reporting basis ever changes, or you need to double-check a figure with a tax agent, the information needed to reconstruct the correct treatment is already sitting in your records rather than needing to be pieced together after the fact.

A practical habit

The simplest way to stay on top of this is to know, plainly, which basis your business reports under, and to keep that fact somewhere you won't forget it — alongside your BAS lodgement dates and registration details. From there, the day-to-day habit is just consistency: record transactions with both relevant dates, and let that consistency do the work of keeping each BAS period accurate, whichever method applies to you.