Quarterly BAS and GST for Pty Ltd Companies: 2026 Guide

The Business Activity Statement is the workhorse of Australian tax compliance. Every quarter, GST-registered businesses report and pay GST, withheld payroll tax, and advance company tax in a single combined return. Get it right and the ATO won't trouble you. Get it wrong and Failure to Lodge penalties stack up at A$330 per 28 days.

This guide covers everything an Australian Pty Ltd founder needs to know about BAS in 2026.

When you must register for GST

Mandatory registration applies if any of:

• Annual GST turnover ≥ A$75,000 (A$150,000 for non-profits)
• You're a taxi or ride-share driver (no threshold — register from day one)
• You want to claim fuel tax credits

"GST turnover" is your gross business income excluding GST and excluding sales of capital assets. Calculate it on a 12-month rolling basis, both backwards and forwards — register if you've already crossed or expect to cross within 12 months.

Voluntary registration below A$75,000 is allowed and often beneficial for B2B businesses.

The four quarterly BAS due dates

The default lodgement cycle for businesses with turnover < A$20m:

Tax agents lodging electronically generally get a 4-week extension for each quarter — but you must be on the agent's lodgement list before the original due date.

Businesses with annual turnover ≥ A$20m must lodge monthly, due 21st of the following month.

What goes on the BAS

The BAS combines several taxes. The fields you'll see:

GST (G1–G20)

• G1 Total sales (including GST)
• G2 Export sales
• G3 Other GST-free sales (basic food, education, health, etc.)
• G10 Capital purchases
• G11 Non-capital purchases
• 1A GST on sales (output tax)
• 1B GST on purchases (input tax credits)

Net GST = 1A − 1B. Pay if positive, refund if negative.

PAYG Withholding (W1–W4)

• W1 Total wages paid to employees (GST-exclusive)
• W2 Tax withheld from employees
• W4 Other withholding (interest, royalties to non-residents)

Pay W2 + W4 to the ATO with the BAS.

PAYG Instalment (5A)

The advance company tax computed by the ATO based on prior year. Pay this to the ATO with the BAS. You can vary it downwards if expecting lower current-year tax (with interest charge if you under-vary by more than 15%).

FBT Instalment (6A)

Quarterly Fringe Benefits Tax payment if your prior-year FBT was over A$3,000. Reconciles with the annual FBT return (separate, due 21 May).

Worked example: Q1 BAS for a small Pty Ltd

Acme Pty Ltd — quarter ended 30 September 2025:

• Sales (GST-inclusive): A$110,000 → G1 = A$110,000
• GST on sales: A$10,000 → 1A = A$10,000
• GST-bearing purchases (rent, software, equipment): A$22,000 → G11 = A$22,000
• GST credits: A$2,000 → 1B = A$2,000
• Wages paid (gross): A$30,000 → W1 = A$30,000
• PAYG withheld from wages: A$5,500 → W2 = A$5,500
• PAYG instalment per ATO: A$3,000 → 5A = A$3,000

Total payable: A$10,000 (GST) − A$2,000 (credits) + A$5,500 (W2) + A$3,000 (5A) = A$16,500

Due 28 October. Pay via BPAY using your unique BAS reference number, direct debit, credit card or bank transfer.

Reverse charge and imported services

Like most VAT/GST systems, Australia applies a reverse charge to certain imported services. Buy A$1,000 of US-based SaaS and the supplier doesn't charge GST — you account for both the GST you would have paid AND the input credit on your BAS, net zero, but it must be reported.

This applies to:

• Services or digital products from non-residents (when you're not GST-registered or not making taxable supplies, the reverse charge is more complex; for a typical Pty Ltd making taxable supplies it's net-neutral)
• Importation of low-value goods over A$1,000 (with customs)

Most accounting software handles this automatically once you flag the supplier as non-resident. Forgetting it is the #1 finding in ATO BAS audits.

GST-free vs input-taxed

Three GST states confuse founders:

GST-free includes most basic food, education, healthcare, exports, and water/sewerage.

Input-taxed includes residential rent, financial services (lending, insurance), and supplies of pre-existing residential premises.

Most owner-managed businesses make purely taxable supplies — no nuance needed. If you're in property or finance, get specific advice.

Penalties for missing the BAS

Failure to Lodge (FTL):

• 1 penalty unit per 28 days late, max 5 units
• Penalty unit (from 1 July 2024): A$330
• Maximum FTL: A$1,650 per BAS

General Interest Charge (GIC) on unpaid GST/PAYG:

• Approximately 11.36% per annum (FY26) compounded daily

For repeated lateness, the ATO can also:

• Cancel any agent extensions
• Issue a Director Penalty Notice making directors personally liable for unpaid PAYG and superannuation
• Initiate an audit

Common mistakes

• Claiming GST on entertainment. s32-1 ITAA 1997 disallows entertainment deductions, and GST input credits follow the same rule.
• Claiming GST on private expenses. Even on a business credit card, private items don't get input credits.
• Forgetting the reverse charge on imported software.
• Claiming GST on motor vehicles above the car limit. Capital allowance and GST credit are both capped at the car limit (A$69,674 from 1 July 2024).
• Missing the deadline because you assumed your tax agent's extension applies — it only applies if you're on their lodgement list.

Direct debit and payment plans

The ATO offers:

• Direct debit for the BAS amount on the due date
• Payment plans for businesses that can't pay the full amount immediately (interest applies)
• Pay As You Go payment via BPAY in advance

If cash flow is tight, contact the ATO before the due date — they're far more flexible if you reach out before defaulting than if you wait for an enforcement letter.

How AccountsOS handles BAS

AccountsOS is live in Australia and runs the entire BAS workflow:

• Categorises transactions by GST treatment automatically
• Detects reverse-charge purchases from non-resident suppliers
• Reconciles to bank statements
• Generates the BAS PDF / electronic submission
• Tracks the four quarterly deadlines and reminds you 14 and 7 days ahead
• Maintains the running PAYG instalment ledger

Try AccountsOS free or read about AccountsOS in Australia.

Related reading

• Company tax in Australia: 25% vs 30% explained
• Superannuation Guarantee 2025: 11.5% to 12% transition
• Single Touch Payroll Phase 2 for small business
• Pty Ltd vs sole trader: choosing your structure