BAS Statement Guide: Due Dates & How to Lodge

A Business Activity Statement (BAS) is the form Australian businesses use to report and pay several tax obligations to the Australian Taxation Office (ATO). For most small businesses the main item is GST, but a BAS can also cover PAYG withholding, PAYG instalments, and other amounts depending on how the business is registered. This guide walks through the reporting cycles, how due dates generally work, the ways you can lodge, and how to prepare the figures from your own records. For a plain-English definition of the form itself, see what is a BAS statement.

Who needs to lodge a BAS

If your business is registered for GST, the ATO will send you a BAS to complete for each reporting period. Registration is generally required once your GST turnover reaches the threshold, and some businesses register voluntarily below it. The exact obligations on your BAS depend on what you are registered for, so the safest source of truth is the official guidance at the ATO.

Reporting cycles

Your reporting cycle determines how often you complete a BAS. The ATO sets the cycle based largely on your GST turnover, and there are three common patterns.

• Quarterly — a common cycle for small businesses. You report figures for each three-month period across the financial year.
• Monthly — typically used by businesses with higher turnover, where the ATO requires more frequent reporting.
• Annually — available to some smaller businesses that have elected to report GST once a year, usually those registered voluntarily and under the relevant turnover threshold.

Because cycles are tied to turnover and to elections you have made, two businesses can be on different schedules. Check which cycle applies to you on your own BAS or through your ATO records, since lodging on the wrong frequency creates avoidable problems.

How due dates work

Due dates follow a predictable structure, but the specific calendar dates shift from year to year and differ by cycle, so it is important not to treat any single date as fixed. As a general rule:

• Quarterly BAS is due roughly a few weeks after the end of each quarter. The exact day for each quarter is published by the ATO and can move when it falls on a weekend or public holiday.
• Monthly BAS is generally due not long after the end of each month.
• Annual GST returns have their own deadline tied to the end of the financial year and your income tax position.

If a due date lands on a weekend or public holiday, lodgement is usually accepted on the next business day. Lodging through a registered BAS or tax agent can also change the dates that apply to you, often allowing extra time. Always confirm the current, exact due dates for your cycle directly with the ATO, because they are the authoritative and up-to-date source — do not rely on remembered dates from a previous year.

Lodgement methods

There are several ways to lodge a BAS, and you can choose whichever suits how your business operates.

• Online through the ATO — many businesses lodge through ATO online services, including via myGov-linked accounts for sole traders or the Online services for business portal for companies.
• Through accounting software — some bookkeeping and accounting tools can prepare and lodge a BAS directly when connected to the ATO.
• Through a registered agent — a registered BAS agent or tax agent can lodge on your behalf, which is common for businesses that prefer to outsource compliance.
• By paper — a paper form is still an option for some businesses, though electronic lodgement is increasingly the default.

Even if your BAS reports nothing for a period — for example, no sales and no purchases — you generally still need to lodge a "nil" statement so the ATO knows the period is accounted for. Confirm the lodgement channels available to you on the ATO site.

Preparing your figures from records

The reporting itself is straightforward once your underlying numbers are accurate. The work that matters is making sure your sales, purchases, and any withholding are captured correctly before you fill in the form.

A reliable BAS starts with clean, complete records. That means every business transaction is recorded, GST is correctly separated where it applies, and your figures reconcile back to what actually moved through your accounts. Comparing your books against your bank records is a good way to catch missing or duplicate entries before they flow into a BAS — see what is a bank reconciliation for how that process works.

If your transaction history only exists as bank statement PDFs, getting it into a spreadsheet first makes categorising income and expenses simpler. You can use the free bank statement converter to turn statements into clean rows, then sort and total the figures you need for each label on the BAS. A detailed walkthrough of that specific workflow is covered in prepare a BAS from bank statements.

Common points to get right

• Keep records as you go. Reconstructing a quarter at the last minute is where errors creep in. Recording transactions throughout the period keeps the numbers honest.
• Separate GST correctly. Not every transaction includes GST, and getting the treatment right matters for the amounts you report.
• Lodge on time, even when nil. A nil BAS still needs to be submitted for the period.
• Confirm dates each cycle. Because due dates move and depend on your cycle and any agent arrangement, verify them with the ATO rather than assuming.

Where to go next

A BAS is mostly an exercise in accurate bookkeeping followed by a structured report. Get the records right, confirm your reporting cycle and current due dates with the ATO, and choose the lodgement method that fits your business. If you are still working out what the form covers in the first place, start with what is a BAS statement. When you are ready to pull your numbers together, the bank statement converter is a practical first step toward clean, reconcilable figures.