If you’re registered for GST, you need to lodge a Business Activity Statement (BAS) — usually quarterly, monthly if your turnover is higher. Here’s exactly how to do it, followed by the due dates and common mistakes worth knowing about.

How to Lodge Your BAS Online in 5 Steps

1. Reconcile your accounts first. Before you touch the BAS form, make sure your bank accounts are fully reconciled and every transaction is coded correctly (especially GST codes — this is where most errors start).

2. Check your GST figures. Confirm your GST collected (on sales) and GST paid (on purchases) match your accounting software’s reports for the period.

3. Include PAYG withholding, if you have employees. If you have staff, your BAS also reports the tax withheld from their wages during the period.

4. Lodge through the right channel. You can lodge via the ATO’s Online Services for Business portal, through your registered tax or BAS agent’s software, or via your accounting software if it’s SBR-enabled (Xero, MYOB, and QuickBooks all support direct lodgement).

5. Pay what’s owed by the due date. Lodging on time doesn’t help if the payment is late — the ATO tracks these separately, and both attract penalties if missed.

If that sounds straightforward in theory but you’re not confident your figures are right, that’s exactly what a Registered BAS Agent checks before anything gets submitted — see below.

Critical BAS Due Dates for 2026

Quarterly lodgers:

• Q1 (Jul–Sep): 28 October
• Q2 (Oct–Dec): 28 February
• Q3 (Jan–Mar): 28 April
• Q4 (Apr–Jun): 28 July

Monthly lodgers: Due on the 21st of the following month.

H2: The Most Common BAS Mistakes

• Wrong GST coding. Claiming GST on GST-free items (like most basic food, or certain health services) is one of the most common errors we see.
• Missing the payment deadline while lodging on time. These are tracked separately by the ATO — get both right.
• Not reconciling before lodging. A BAS built on an unreconciled bank account is a guess, not a report.
• Overlooking PAYG withholding for casual or part-time staff. It’s easy to assume small payroll doesn’t need the same rigour — it does.

What Changes with STP Phase 2 and Payday Super in 2026

If you have employees, two changes are worth understanding alongside your BAS:

Single Touch Payroll (STP) Phase 2 requires payroll data to be reported to the ATO broken down by category — ordinary hours, overtime, allowances, and leave — rather than as a single gross figure. This needs to be set up correctly in your payroll software, not adjusted after the fact.

Payday Super, since 1 July 2026, requires super contributions to reach your employee’s fund within 7 business days of each pay run, rather than quarterly. This is a genuine change to how most small businesses have operated, and it affects your cash flow timing as well as your compliance.

Neither of these is something you need to memorise — they’re things your bookkeeper or BAS agent should already have built into your regular process.

Should You Lodge BAS Yourself, or Use a Registered BAS Agent?

Lodging your own BAS is completely legal, and plenty of business owners do it — particularly with simple, low-transaction-volume businesses. It tends to make sense to bring in a Registered BAS Agent when:

• You have employees and payroll obligations alongside your BAS
• You’ve been unsure about a previous lodgement, or received an ATO query
• BAS prep is consistently taking hours you don’t have
• You want someone who can talk to the ATO directly on your behalf if something comes up

As Registered BAS Agents based on the Central Coast, we handle BAS lodgement for businesses who’d rather have it checked and submitted by someone qualified to do it — with the added benefit of extended lodgement deadlines in most cases.

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