How to complete a BAS statement for monthly or quarterly lodgment

A BAS isn’t just a GST form: according to the Australian Taxation Office, it can report GST and PAYG amounts. To understand how to complete a BAS statement, match the figures to the right reporting period, reconcile them with your records, then lodge and pay by the due date on your statement. Businesses generally need to register for GST when their annual turnover exceeds $75,000, according to the Australian Taxation Office.

BAS paperwork can feel like one more task competing with customers, staff and day-to-day decisions. Organised records and the right accounting software make preparing and lodging a statement easier to manage. This guide explains how a BAS relates to GST, who may need to lodge, what to gather and how to complete and submit a monthly or quarterly statement. It also covers due dates and online lodgment, so you can plan for your next BAS.

What is a business activity statement (BAS)?

Start by identifying the taxes listed on your activity statement and the reporting period it covers. Match each relevant figure to your business records and registrations.

1. Understand what the BAS reports

   Check which taxes and payments your business must report. A business activity statement can include GST, PAYG withholding and PAYG instalments; other applicable items include fringe benefits tax instalments, wine equalisation tax and fuel tax credits. The fields depend on your registrations, so complete only the sections that apply. Accurate figures show what you owe or can claim for the reporting period.

2. Report PAYG amounts

   Use payroll records to report PAYG withholding, which is tax withheld from payments such as employee wages. Report PAYG instalments separately: these are payments towards expected income tax. Enter each amount in its corresponding section, then compare the figures with payroll and accounting records. Keep withheld tax distinct from instalments rather than combining different obligations.

3. Follow the labels printed on your BAS, because your statement is tailored to your registrations. For the GST labels, G1 is total sales, 1A is GST on sales, and 1B is GST on purchases. Include the figures that apply to your business, using the right reporting period and accounting basis. Check that your sales and purchase amounts reconcile with your records before lodging.
4. Use the accounting basis that applies to your GST reporting. The accounting basis used for GST reporting affects when transactions should be included in a BAS. This affects which sales and purchases belong in the BAS period. Match each transaction to the correct period, then reconcile the totals with your source records before entering them.
5. Check whether annual reporting applies before preparing a monthly or quarterly activity statement. Businesses generally need to register for GST when their annual turnover exceeds A$75,000, according to the Australian Taxation Office. Businesses voluntarily registered for GST with turnover under A$75,000 may be eligible to report annually; the threshold is under A$150,000 for not-for-profit bodies. Eligible annual reporters lodge by 31 October.

An Australian BAS can also report luxury car tax, alongside GST, PAYG withholding and instalments, fringe benefits tax instalments and wine equalisation tax.

Lodging by mail, online or through an agent

Choose an accepted lodgment method and follow the instructions on your BAS. Late lodgment or payment may result in penalties and interest from the Australian Taxation Office. The amount depends on your circumstances.

1. Choose an online option that suits your setup. Lodge through ATO Online services for business or compatible SBR software. Sole traders can use a linked myGov account, while phone lodgment is available for nil statements. Before submitting, confirm that the statement covers the correct reporting period and all applicable fields are complete. Save the lodgment confirmation with your business records in case you need to follow up.
2. Complete and return a paper BAS by mail if you prefer. Use the form sent to your business, enter figures clearly and follow its return instructions. Check that the payment details match your BAS before paying any amount due. Keep a copy of the completed form and note when you sent it. Allow enough time for delivery before the due date printed on the statement.
3. Use a registered tax or BAS agent when you need help preparing or lodging. This can be useful if your records need reconciling, your business has several reporting obligations, or you want support with recurring statements. Anyone preparing a business’s BAS should be registered with the Tax Practitioners Board. An unregistered agent does not provide the same protections. Agree on who will prepare, lodge and pay, and keep your own copies of records and confirmations.
4. Act promptly if a deadline is at risk. If you can’t lodge or pay by the date shown, contact the Australian Taxation Office as soon as possible. If you owe money but can’t pay in full, the ATO offers payment plans to businesses experiencing difficulty. Lodging and paying are separate tasks, so arranging payment does not submit your statement. Keep notes of ATO communications and follow the agreed next steps.

Before lodging, compare the final statement with your accounting records and submit it using your chosen channel. If an agent lodges for you, confirm that the statement was submitted and save the confirmation with your BAS records.

Late BAS lodgment or payment can lead to ATO penalties and interest. The amount varies according to your circumstances.

Monthly and quarterly BAS due dates

Plan lodgment and payment around the due date printed on your BAS. Your reporting cycle and lodgment method can affect the deadline.

1. Confirm your reporting cycle. Australian businesses may have monthly, quarterly or annual BAS periods, as notified by the ATO after registration. Businesses with GST turnover below $20 million generally report quarterly unless the ATO requires monthly reporting. Businesses with GST turnover of $20 million or more report monthly. Businesses with annual turnover of $20 million or less may choose monthly or quarterly lodgment. Use the cycle shown on your statement, rather than assuming it stays the same as your business changes.
2. Mark monthly deadlines in your calendar. Monthly BAS lodgment and payment are due on the 21st day of the following month. For example, the statement covering July is due on 21 August. Set a reminder to gather figures and review the statement before that date. The deadline covers both lodging the BAS and paying any amount due, so plan for both tasks instead of treating payment as a separate later step.
3. Record each quarterly due date against its reporting period. The July-September quarter is due on 28 October. The October-December quarter is due on 28 February, the January-March quarter on 28 April, and the April-June quarter on 28 July. Quarterly BAS is generally due on the 28th of the month after each quarter. Write the period beside each deadline to avoid mixing up a quarter’s end date with its lodgment date.
4. Check whether an extension applies to your lodgment method. Businesses lodging a quarterly BAS online may be eligible for an additional 2 weeks to lodge and pay. A tax agent may also have later lodgment dates than the general deadlines. These extensions don’t mean you should ignore the due date printed on your statement. Confirm the applicable date for that BAS and make sure payment timing matches it.
5. Include annual reporting in your schedule when eligible. Australian businesses voluntarily registered for GST may be eligible to report annually if their GST turnover is under $75,000, or under $150,000 for not-for-profit bodies. Eligible annual reporters lodge by 31 October. A common planning mistake is to assume every business follows quarterly dates, so check your statement’s reporting period and due date before setting reminders.

Pay a BAS using BPAY, direct credit or the ATO’s online services. If you can’t pay by the due date, contact the ATO as soon as possible to discuss a payment plan.

Accounting software and electronic lodgment

Use accounting software to organise business figures and prepare BAS calculations. Then lodge through an online channel that suits your records and reporting process.

1. Use accounting software for lodgment

   Set up your accounting records to capture sales, purchases and other transactions in the correct reporting period. To complete a BAS statement, use software to bring relevant figures together, then check them against source records. Automation doesn’t replace review: confirm your business registrations and obligations match the statement. It’s easier to correct a coding or timing error before lodgment than to explain an inconsistent figure later.

2. Lodge through the ATO or software

   Lodge online through ATO Online services for business or SBR software. Start with the BAS for the correct reporting period, review each applicable field, then submit it according to the channel’s instructions. Sole traders can also lodge through a linked myGov account. Check the submitted figures against your accounting records and save the confirmation with the relevant BAS documents.

3. Review software figures before approving a statement. Check sales and purchases against invoices and accounting entries for the reporting period. Compare GST figures with the underlying transactions, and check payroll records where PAYG withholding applies. Look for uncategorised or duplicated entries that could affect totals. Software-generated figures are useful only when the underlying transactions are complete and assigned to the right period.
4. Keep a clear trail from records to lodgment. Save the BAS calculation, supporting reports and confirmation together, so you can trace reported amounts back to business transactions. If a figure changes during review, note which entry changed and why. This makes later questions easier to investigate and helps keep your accounting file consistent with the submitted activity statement. Most Australian BAS are lodged online, but retain the records that explain your figures.

Knowing how to complete a BAS statement means having a repeatable process: organise records, review calculated amounts, submit through the ATO or SBR software, then save the confirmation. Following these steps connects accounting data with reporting obligations without treating automation as a substitute for careful review.

Online lodgment is not the only option: Australian businesses can lodge a BAS through a registered tax or BAS agent, ATO Online services for business or SBR software, a linked myGov account for sole traders, by phone for nil statements, or by mail.

The accounting basis used also affects the amounts reported on an Australian BAS.

What information and records are needed to complete a BAS?

Gather records for the exact BAS period before entering figures. Keep invoices, bank activity, wage records and ATO correspondence together so each amount is easy to trace.

1. Collect sales and purchase records for the reporting period. Set aside tax invoices, receipts and other purchase records, then match them to sales and expenses in your accounts. Use the transaction date and your accounting basis to determine which period each item belongs to. For example, compare a supplier invoice with its recorded purchase entry rather than relying on a bank total alone. This helps identify missing, duplicated or misclassified transactions before they affect BAS figures.
2. Reconcile bank statements with your business records. Compare deposits and payments with sales and purchase entries for the same period. Investigate differences, such as a deposit without a corresponding sales record or a recorded payment missing from the statement. A bank statement supports reconciliation, but doesn’t explain every transaction by itself. Keep the related invoice or receipt as supporting evidence for each amount.
3. Prepare employee wage details if you report PAYG withholding. Gather payroll summaries and wage records for the BAS period, then compare the totals with the amounts in your accounts. Check that the figures relate to the same period as the statement. Keep records that explain how the reported withholding was calculated, including any payroll adjustments. This creates a clear trail from employee payments to the amount entered on the BAS.
4. Keep ATO correspondence with the records for that BAS. File notices and messages relating to your reporting obligations, payments or statement details. Retain any information from the Australian Taxation Office that relates to the BAS alongside supporting transactions and calculations. A dated note explaining an adjustment can also help you understand the figures later. Organise records by reporting period so you can find the right documents without mixing them with another statement.
5. Check the statement against your source documents before lodging. Compare each BAS amount with the underlying sales, purchases, bank activity or wage details. Confirm that the transactions belong to the reporting period and that the figures match your accounting records. Australian businesses should retain BAS-related financial records for at least five years. Keep the completed statement and supporting documents together, whether stored digitally or on paper.

Business Wise: Business Accounting and Advisory

Business Wise is a family-owned firm supporting business owners in Rockhampton. If BAS tasks are taking time from customers and day-to-day decisions, its Bookkeeping & BAS Services can help with the practical work of keeping business records and activity statements in order.

For owners balancing paperwork with running a local business, Business Accounting and Advisory can connect financial management with broader business decisions. The aim is to make your numbers more useful as you plan your next steps.

Contact Business Wise to discuss support for your business.

Make your next BAS part of a steady routine

A reliable BAS process can become part of running your business rather than a last-minute scramble. Set a recurring time to review your accounts, resolve unusual transactions and prepare for the next reporting period. As your business changes, revisit whether your records and accounting process still support your reporting. This habit can help you focus on decisions that move your business forward.

Learning how to complete a BAS statement is a useful step, but you don’t have to manage every accounting task alone. Business Wise offers Business Accounting and Advisory, Bookkeeping & BAS Services, and Tax Advisory to support business owners with their financial responsibilities.

Contact Business Wise for BAS help, and take your next step with greater clarity.

Frequently Asked Questions

How does BAS relate to GST?

GST is one of the taxes a business may report through its BAS. The BAS is the reporting statement, and GST is one set of figures entered on it. For example, a GST-registered business records sales and purchases for the relevant period, then reports applicable GST amounts. The statement can also cover other obligations, so GST isn’t the only reason a business might receive a BAS.

What if I make a mistake on my BAS?

Identify the affected statement, reporting period and figure, then compare it with the records behind the entry. Keep the relevant invoices, bank records or payroll details together so the source of the error is clear. If you’ve already lodged the BAS, contact the Australian Taxation Office or a registered tax or BAS agent for guidance on correcting it. Don’t change your bookkeeping without addressing the submitted statement.

What is BAS?

A business activity statement, or BAS, is a form Australian businesses use to report applicable taxes and payments. Depending on a business’s registrations and obligations, it may include GST, PAYG withholding or PAYG instalments. A BAS isn’t a sales invoice or profit statement: it summarises required information for a reporting period. Check the statement issued to your business, as its fields are tailored to your registrations.

Who needs to lodge a BAS in Australia and how often?

Businesses registered for GST generally lodge activity statements, including sole traders, while the ATO sets or notifies them of the reporting cycle. Monthly and quarterly periods are common; eligible businesses voluntarily registered for GST may report annually. Special rules apply to taxi and ride-sharing drivers, who must register for GST regardless of turnover. Taxi travel providers and businesses claiming fuel tax credits also have GST registration and BAS obligations.

How do you report GST sales and purchases on a BAS?

Use the BAS labels that apply to your statement and report the transactions belonging to its period. G1 records total sales, while 1A and 1B record GST on sales and purchases respectively. For example, use invoices and purchase records to trace the reported amounts back to individual transactions. Apply your accounting basis consistently, since it affects which period includes a sale or purchase.

How do you calculate GST payable or refundable on a BAS?

Compare the GST on sales reported at 1A with the GST on purchases reported at 1B. If 1A is greater, the difference contributes to the amount payable; if 1B is greater, the statement may show a refund or credit position. Check each figure against eligible transactions and the records for that reporting period. Other BAS amounts can affect the final balance due.

What are the BAS lodgment and payment due dates in Australia?

Use the date printed on your BAS as the key deadline for lodging and paying. Monthly statements are generally due on the 21st of the following month; quarterly statements are generally due on the 28th of the month after the quarter. For example, the July-September quarter is due on 28 October. Online quarterly lodgers may be eligible for an additional two weeks, and tax agents may have later dates.

Article by

Lloyd Priddle

Lloyd has been in the industry for over 30 years and has worked in a number of domestic and international firms.