Australian tax reporting

What is a Business Activity Statement (BAS)?

What is a BAS in Australia. Infographic with Australian styling: sample activity statement labels for GST and PAYG, a calendar, and ATO references.

A Business Activity Statement (BAS) is the form businesses use to report and pay several tax obligations to the Australian Taxation Office (ATO), most often goods and services tax (GST), pay as you go (PAYG) withholding, and PAYG instalments. If you are registered for GST, you will usually lodge a BAS for each period (monthly, quarterly, or annual for some small businesses) and pay by the due date shown on the form. Your valid tax invoices and payment records are the source data behind the sales, purchases, and withholding labels you complete. The BAS is separate from your annual income tax return, though both rely on good bookkeeping. Lodging a nil activity statement is still required when you have no amounts to report but a statement is due.

Quick reference

BAS, GST, and PAYG in plain terms

Use these definitions with your bookkeeper, BAS agent, or payroll so everyone maps invoices and pay runs to the same labels.

What is a BAS in Australia?

A Business Activity Statement (BAS) is how eligible businesses report and pay certain taxes and amounts to the ATO, including GST, PAYG instalments, PAYG withholding, and other taxes that apply to your situation. The ATO explains that, when you register for an Australian business number and GST, it will generally send you a BAS when it is time to lodge. The due date for lodging and paying appears on your BAS. Even if you have nothing to report for a period, you may still need to lodge a nil statement by the due date.

  • Covers more than one tax type when your registration requires it
  • Period and due dates depend on ATO settings and your reporting cycle
  • Uses labels (such as G1, 1A, 1B, and W1 to W5) that must match your records
  • Lodge and pay on time to reduce interest and penalties

Example

You run a design studio and report GST quarterly. Each quarter you copy total sales, GST on sales, and GST on purchases from your books into the GST section, check PAYG withholding from your payroll, then lodge online and pay the net amount owing by the due date.

How does GST go on a BAS?

If you are GST registered, the GST section of your BAS summarises your taxable sales and the GST you collected, plus credits for GST included in business purchases, subject to the rules. The ATO hub links detailed instructions to labels G1, G2, G3, G10, G11, G21, G22, G23, G24, 1A, and 1B. The exact labels you complete depend on your method and your obligations for that period.

  • Reconciles the GST on your valid tax invoices with your reported figures
  • You must use a GST reporting method that matches your registration
  • Mistakes here can affect your next BAS and your income tax return
  • Simpler BAS and bookkeeping rules can apply to very small businesses that qualify

Example

You use the accounts method, total your tax invoices for the quarter, and report total sales at G1, then work through purchases and the GST in their price in line with ATO guidance to reach 1A and 1B.

What is PAYG withholding in the BAS context?

When you withhold tax from employees or from suppliers who do not quote an ABN, you report those amounts in the PAYG withholding section of your BAS. The ATO provides label guidance including W1 (total payments), W2 (amounts withheld from those payments), W3 (other withholding), W4 (withholding where no ABN is quoted), and W5 (total of W2, W3, and W4). The ATO states that you must pay the withheld amounts to the ATO, which is how employee and supplier withholding connect to your activity statement.

  • Aligns with Single Touch Payroll reporting for many employers
  • W4 captures no-ABN withholding, which is why invoice details matter
  • Get label help from your payroll platform or tax agent if you are unsure
  • Late or incorrect withholding can create gaps between your pay runs and your BAS

Example

Your payroll software totals salaries for the month at W1 and tax withheld at W2. A contractor invoice without an ABN triggers withholding at 47% for the relevant part of the payment, which you report at W4 when those rules apply.

Side-by-side

BAS vs instalment notice vs income tax return

A full BAS is your main activity statement for GST and other obligations. Some businesses receive a simpler GST or PAYG instalment notice instead. Your annual income tax return is a different return that covers income tax after the year ends.

Primary job

BASReport and pay GST, PAYG withholding, PAYG instalments, and other labels that apply in one period
Instalment noticeReport or pay set GST or PAYG instalment amounts, sometimes without a full BAS, when the ATO tells you that model applies
Income tax returnWork out annual income tax for the entity or person, including deductions, offsets, and final tax

Typical timing

BASMonthly, quarterly, or (for some small voluntary GST registrations) annual GST reporting, depending on turnover and ATO settings
Instalment noticeOften quarterly, following ATO notices
Income tax returnOnce a year for most entities, with due dates in ATO guidance

Tie to every invoice

BASStrong: your GST labels should trace back to tax invoices and business purchases
Instalment noticeWeaker: some notices use pre-printed or instalment amounts you pay as directed
Income tax returnVaries: supports profit and loss for the year, not each BAS period

If you are registered for GST

BASYou will usually lodge a BAS as your main GST return unless the ATO moves you to a different pattern
Instalment noticeYou may get a quarterly GST instalment notice instead of a full BAS in certain cases
Income tax returnYou still need an annual income tax return where required, on top of GST reporting

Practical guidance

When a BAS matters to your business

You work with a BAS when the ATO expects you to report GST, PAYG withholding, PAYG instalments, or other labels attached to your registration. The schedule on your form drives when you act.

GST-registered businesses

The ATO states that, if you are a business registered for GST, you need to lodge a BAS. Your form helps you report and pay GST, PAYG instalments, PAYG withholding tax, and other taxes as they apply. Online lodgment is common, and a registered tax or BAS agent can lodge for you.

  • You pass the GST turnover test or voluntary registration applies
  • You need to show GST on tax invoices and back those figures in each BAS period
  • You claim GST credits on business purchases in line with ATO rules
  • You adjust when you find invoice or setup errors in earlier periods

Match your first BAS period to the ATO's GST effective date so you do not double count or miss a month.

Employers and withholding

Employers and others who withhold from payments report PAYG withholding on the BAS when required. The label list includes W1 and related fields. The ATO reminds businesses that the due date to lodge and pay is shown on the BAS, and you must pay withheld amounts in full and on time.

  • You run payroll and withhold Pay As You Go tax from wages
  • You withhold from interest, dividends, or other payments in listed cases
  • A supplier does not quote an ABN and you must withhold and report (label W4 when rules apply)
  • You are classified as a large withholder, which changes which labels you use

Reconcile pay runs to your BAS before you lodge, especially after back pay or one-off bonuses.

Reading due dates and cycles

The ATO explains that your GST reporting and payment cycle may be monthly (for larger GST turnover or when you choose it), quarterly when turnover is under $20 million and monthly reporting is not required, or annual when you are voluntarily registered for GST and your GST turnover is under the small-business threshold for that option. The due date for lodging and paying appears on your BAS, and if you lodge online for quarterly BAS, you may get an additional two weeks in many cases.

  • You set calendar reminders from the date printed on each BAS, not a guess from memory
  • You use BPAY, card, or other ATO options with the correct reference number for payment
  • You line up your net thirty or other client payment terms with cash you need before the BAS is due
  • You work with a BAS agent who may have a different concessional due date for lodgment

Update your ATO contact details so email notices arrive before the due date the ATO shows on the statement.

What sets them apart

BAS, invoices, and other reporting

Your BAS summarises the tax period. Tax invoices and payroll are evidence. STP sends payroll information to the ATO but does not replace your BAS when you have GST or other BAS labels to complete.

BAS versus each tax invoice

Every tax invoice is a line in your story. The BAS is the chapter summary. Totals in G1, 1A, and 1B should be explainable from your invoice list, not a single rounded guess.

BAS versus net thirty and cash timing

Net thirty sets when your customer should pay. Your BAS is still due on the ATO date, even if a large invoice is still outstanding, so you plan cash to cover the BAS payment.

BAS versus U.S. ACH and card culture

United States customers might pay you through ACH in their banking network. The payment method does not change which Australian BAS labels you use, but the currency and bank fees can affect the amounts you record in your books.

BAS and annual reporting

Think of the BAS as shorter-cycle compliance. The income tax return is usually annual and can adjust timing differences that BAS periods only estimate through instalments.

Workflow

How to get from invoices to a lodged BAS

Close your books for the period, reconcile GST and payroll, complete each label, lodge electronically where possible, then pay using ATO methods before the due date. Keep source documents for at least five years in line with record-keeping rules.

  1. 1

    Finish bank and invoice reconciliation

    Match every business transaction for the period, including part-month payroll and part-period contractor bills. Fix coding errors now so the BAS is not a patch-up later.

    Tip: Flag invoices that are missing ABNs before you run withholding.

  2. 2

    Reconcile GST from tax invoices and purchases

    For your chosen reporting method, work from valid tax invoices and import documents that meet the rules. The ATO's instructions for each label are the authority when you are unsure which sales sit at G1.

    Tip: If you use accounting software, print a label checklist before you transfer figures.

  3. 3

    Complete PAYG withholding from payroll and other payments

    Total gross wages at W1 when you must, and align withheld amounts to what you have already sent through STP or your process. Add other withholding, including W4, when a supplier has not quoted an ABN in line with the rules.

    Tip: Large withholders and special cases should follow the simplified instructions that apply to them.

  4. 4

    Review net GST and payment due

    Work out whether you pay net GST, receive a refund, or owe PAYG. Cross-check the payment or refund line against your own calculator before you lodge.

    Tip: Round to whole dollars on the form where the instructions require it.

  5. 5

    Lodge and then pay on time

    Lodge your BAS in full through Online services, myGov, SBR software, an agent, or the channel you use. Pay using BPAY, card, or another listed option with your unique reference, because the ATO points out you must pay in full and on time to avoid interest.

    Tip: If you are short on cash, use ATO support pages about paying in full and on time before the due date passes.

  6. 6

    File documents and plan the next period

    Save the lodged BAS, payment confirmation, and working papers. Set the next review date for invoices and pay runs before the next due date, especially if your clients use net thirty or net sixty by default like many United States and Australian B2B contracts.

    Tip: A short post-lodgment review catches one-off errors early.

Pitfalls

Mistakes that throw out your BAS

The usual problems are late reconciliation, wrong GST on mixed supplies, and forgetting to lodge a nil statement. Fix habits, not just numbers.

Rushing the BAS on the due date

Problem

Unreconciled bank feeds mean you guess G1 and hope payroll ties out.

Fix

Block time after month-end or quarter-end, then lodge once figures settle.

Forgetting a nil activity statement

Problem

You had no sales in the period, so you skip lodging entirely.

Fix

Lodge a nil statement when a BAS is due, because the ATO still expects a lodged form.

Mixing private spending through the business account

Problem

Non-business items inflate purchases and GST credit claims.

Fix

Separate cards and recode personal items before you lock the BAS period.

Ignoring no-ABN supplier invoices

Problem

PAYG withholding was required, but you did not withhold or report at W4.

Fix

Follow the ATO's no-ABN rules, withhold where required, and amend the BAS if you discover the issue later.

Assuming the BAS replaces STP or payroll

Problem

Payroll is messy, but you only eyeball W1 and W2.

Fix

Reconcile to payment summaries, STP data, and the BAS so all three match.

Checklists

Checklists before you lodge a BAS

Run these lists so your BAS matches your bank, your payroll, and your tax invoices.

Source records

  • All tax invoices and adjustment notes for the period are in your ledger
  • ABN, GST, and line items match what buyers and suppliers were told
  • PAYG withholding, including no-ABN cases, is documented
  • Foreign currency transactions converted using consistent rules

GST and sales

  • You can explain every dollar that sits at G1 and related sales labels
  • GST on sales and GST on purchases are consistent with the tax invoices you hold
  • Exempt, input-taxed, and private sales are coded correctly for your method
  • Simpler BAS or special schemes still match your ATO registration

Lodgment and payment

  • The due date on the BAS is in your calendar with buffer for banking cut-offs
  • You use the ATO's payment options with the correct reference number when required
  • A registered BAS or tax agent is engaged where you need representation
  • A nil BAS is still prepared when nothing is due but a statement is issued

Sources

What official Australian sources say about BAS

The lines below paraphrase ATO guidance. Always read the current pages, since thresholds and options can change.

  • The ATO says that, if you are a business registered for GST, you need to lodge a business activity statement, and that your BAS will help you report and pay goods and services tax, pay as you go instalments, PAYG withholding tax, and other taxes. The ATO also says that, when you register for an ABN and GST, it will automatically send you a BAS when it is time to lodge, and that you must pay your BAS in full and on time to avoid paying interest, with a due date for lodging and paying that is displayed on the BAS. The ATO lists BPAY, card through online services, and your unique payment reference as common elements of how you pay, and it explains reporting cycles including quarterly reporting when your GST turnover is under $20 million, monthly when turnover is at least $20 million, and annual for some voluntary small-business registrations. It also notes you may be eligible for an additional two weeks to lodge and pay quarterly BAS when you lodge online.

    Australian Taxation Office, business activity statement hub and related pages (2025). View source

  • The ATO's PAYG withholding label guide names W1 as total salary, wages, and other payments, W2 as amounts withheld from salaries, wages, and other payments at W1, W4 as amounts withheld where no ABN is quoted, W3 as other amounts withheld excluding W2 and W4, and W5 as the total of W2, W3, and W4. The guide also states you must pay withheld amounts to the ATO and that you need to report withheld amounts in the PAYG tax withheld section of your BAS, with large withholder rules that change which fields you use.

    Australian Taxation Office, PAYG withholding label instructions (2024). View source

  • The ATO explains that, when completing the GST part of a BAS, you need to work through labels that include G1, G2, G3, G10, G11, G21, G22, G23, G24, 1A, and 1B, and that it provides full label instructions in its online guides so you can show taxable sales, GST in the price, credits, and adjustments correctly.

    Australian Taxation Office, business activity statement GST instructions hub (2025). View source

Related document types

Notices, agents, and cross-border work

Some businesses receive a quarterly GST or PAYG instalment notice instead of a full BAS. If you have foreign clients, currency and GST-free exports can each change the labels you touch.

When you get an instalment notice instead of a full BAS

The ATO explains you may get a simpler quarterly GST or PAYG instalment notice, instead of a business activity statement, in certain cases. The rules tell you when you can pay a pre-printed amount versus when you must work through a full activity statement, so read the document you actually receive for that period.

BAS agent compared with doing it yourself

The ATO notes that a registered tax or BAS agent can lodge, vary, and pay on your behalf, which can also shift due dates. If you self-lodge, use Online services, myGov, SBR software, or mail in the rare cases still allowed, and follow the ATO's channel-specific guidance.

Exports, GST-free sales, and mixed supply invoices

GST labels change when a sale is GST-free or input taxed. Invoices to overseas clients and certain domestic sales need correct classification, or the BAS and your income tax will disagree later.

Frequently asked questions

Practical questions Australian small businesses ask about the BAS.

What does BAS stand for in Australia?

BAS stands for Business Activity Statement. It is the ATO form you use to report and pay certain obligations such as GST and PAYG withholding, depending on your registration.

Do I have to lodge a BAS if I had no sales this quarter?

If a BAS is issued and due for a period, you may still need to lodge, often as a nil report, so the ATO can see the period is complete. Check the ATO's guidance and your own notice, because the exact requirement depends on your case.

How is a BAS different from my tax return?

A BAS is a periodic return for taxes such as GST and PAYG, following the cycle on your form. The annual income tax return is separate and finalises income tax and offsets for the year, subject to who must lodge.

What is a BAS or tax agent in Australia?

A registered tax agent and a registered BAS agent are professionals you can authorise to prepare and lodge certain statements for you, within the scope the Tax Practitioners Board and ATO set for that registration.

Where do my tax invoices go in a BAS?

You do not usually attach every invoice. Instead, you use them as evidence in your books, then you transfer totals to the right GST, sales, and withholding labels for the period, keeping invoices stored for the record-keeping period.

What happens if I miss a BAS due date?

The ATO may charge interest on unpaid tax and can apply failure-to-lodge penalties when the law allows. If you cannot pay on time, the ATO publishes support options and payment plans, and you should contact them or your agent as early as possible.

Does net thirty on my invoice change my BAS date?

Net thirty changes when the customer should pay you, not the ATO due date on your activity statement, so you plan cash to cover the BAS on time. See the net thirty glossary page for the payment-term meaning.

I only receive United States dollars from clients. Does a BAS still apply?

The currency on your client invoice does not remove Australian GST and BAS rules on its own. Convert and classify income correctly, then complete the correct GST and income labels for your business structure, or get advice where foreign supplies are common.

Is an ACH payment relevant to a BAS like it is in the U.S.?

ACH is a U.S. bank network term. In Australia, bank transfer and direct debit are common, but the BAS is still the same ATO return. The glossary on what is an ACH payment can help you explain U.S. clients who mention that name.

Keep learning

Related guides, glossary, and U.S. comparisons

Ground BAS rules in local guides, then use global glossary pages when you bill overseas clients who speak U.S. or international payment terms.

What is an ABN?

Connect your ABN, GST registration, and BAS reporting before you set default invoice text.

Read glossary entry

Tax invoice requirements in Australia

Get tax invoice fields right so your GST and BAS stay aligned.

Read guide

What is a tax invoice in Australia?

Short glossary take on tax invoices before you reconcile G1 to your issued documents.

Read glossary entry

GST registration and Australian invoicing

When to register and how it affects the BAS periods you can expect from the ATO.

Read guide

Net thirty payment terms

Align customer due dates on invoices with the cash you need for BAS and payroll.

Read glossary entry

What is an ACH payment?

A United States explainer for bank transfers when clients use ACH vocabulary.

Read glossary entry

Australian guides hub

Browse more Australian playbooks on Invoice Mama.

Read guide

Australian glossary

More Australian English definitions for invoicing and tax labels.

Read glossary entry

Business glossary

Global invoicing terms when you also trade with U.S. readers.

Read glossary entry

Free invoice templates

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