Reporting · BAS
BAS lodgement: quarterly vs monthly vs annual
Most SMEs lodge quarterly. The cycle and the due dates flow from your GST turnover and whether a registered agent lodges for you. Here are the cycles, the precise 2026 due dates, the agent extensions and the labels you actually fill in — drawn from ato.gov.au.
★Key takeaways
- ✓Quarterly BAS is the default for SMEs (GST turnover under $20 million).
- ✓Monthly BAS is mandatory at $20 million GST turnover. You can opt in voluntarily below that.
- ✓Annual BAS is only available to voluntary GST registrants below the $75,000 threshold who elect it.
- ✓Self-lodger quarterly due dates: 28 Oct, 28 Feb, 28 Apr, 28 Jul.
- ✓Registered BAS or tax agent extension: typically +1 month (Q1 to 25 Nov, Q3 to 26 May, Q4 to 25 Aug). Q2 has no extension.
- ✓Late lodgement: 1 penalty unit per 28 days (capped at 5 for small entities, ~$1,565 at the $313 unit rate) plus GIC on unpaid tax.
Which cycle
Who lodges monthly, quarterly or annually
| Cycle | Who lodges this way | Self-lodger due date |
|---|---|---|
| Monthly | GST turnover $20 million or more (mandatory); voluntary opt-in available below | 21st of the following month |
| Quarterly | GST turnover under $20 million (default cycle for SMEs) | 28th of the month after quarter-end (see table above) |
| Annual | Voluntary GST registrants below the $75k threshold who elect annual | 31 October following the financial year end (or with income tax return if earlier) |
A small business voluntarily on monthly BAS can switch back to quarterly when growth has stabilised — election through ATO online services. Mandatory monthly cycles cannot be changed below $20m.
2026-27 due dates
Quarterly BAS — self-lodger vs agent
| Quarter | Self-lodger | Registered BAS / tax agent |
|---|---|---|
| Q1 — Jul, Aug, Sep | 28 October | 25 November |
| Q2 — Oct, Nov, Dec | 28 February | 28 February (no extension) |
| Q3 — Jan, Feb, Mar | 28 April | 26 May |
| Q4 — Apr, May, Jun | 28 July | 25 August |
When the due date falls on a weekend or public holiday, the deadline shifts to the next business day. The Q2 (October-December) cycle has no agent extension because the self-lodger date already accounts for the Christmas closedown — it sits at 28 February (59 days after quarter-end) rather than 28 January.
When monthly makes sense
Reasons to voluntarily elect monthly
- You are due net refunds. Exporters and capital-intensive start-ups often have GST input credits exceeding GST on sales. Monthly cycles return cash faster.
- You want tighter cashflow discipline. Monthly forces a habit of clean bookkeeping; quarterly lets bad reconciliation pile up.
- Your business is heavily exposed to international supply. Where reverse-charge GST applies to imports of services, monthly reduces the lag.
- You are scaling fast. Crossing $20 million mid-year forces monthly anyway; some founders flip early to embed the rhythm.
The trade-off is admin: monthly is 12 lodgements a year vs four. If you do not have software-driven bookkeeping, quarterly is generally the right cycle.
What is on the form
Key BAS labels
| Label | What it captures |
|---|---|
| G1 | Total sales (including any GST) |
| G2 | Export sales |
| G3 | Other GST-free sales |
| G10 | Capital purchases |
| G11 | Non-capital purchases |
| 1A | GST on sales |
| 1B | GST on purchases (claimable credits) |
| W1 | Total salary, wages + other payments subject to PAYG withholding |
| W2 | Amount withheld from W1 payments |
| T1 | PAYG instalment income (for income-tax instalments) |
| T7 | PAYG instalment amount payable |
The full label list also includes WET (wine equalisation tax), LCT (luxury car tax), and FBT instalments where registered. Most small businesses encounter only the labels above. Source: ato.gov.au/business/business-activity-statements-bas.
Late lodgement
Penalties + interest
The failure-to-lodge (FTL) penalty is calculated at one penalty unit per 28 days (or part thereof) the statement is late. The cap is five penalty units for a small entity (currently $1,565 at the $313 unit rate), 10 for a medium entity, and 25 for a large entity. The penalty is in addition to general interest charge (GIC) on any unpaid liability, currently around 11.34% annualised.
The ATO will frequently waive the FTL penalty for first-time late lodgers with a clean history. If you know you will be late, call 13 28 66 or contact your registered agent before the deadline — proactive communication usually avoids penalty.
Primary sources
Where the figures on this page come from
- BAS main page: ato.gov.au/business/business-activity-statements-bas.
- Quarterly due dates: ato.gov.au/business/business-activity-statements-bas/due-dates-for-lodging-and-paying-your-bas.
- Tax agent + BAS agent lodgement program: TPB.
- FTL penalty + GIC: ato.gov.au/general/interest-and-penalties.
General information only. Lodging and paying tax obligations should be done through a TPB-registered tax agent or BAS agent if you are unsure. See our disclaimer.
Common questions
BAS lodgement — common questions
What is the default BAS cycle for a new small business?
Quarterly. If you register for GST at start-up and your turnover is under $20 million, the ATO defaults you to quarterly BAS lodgement. You can elect monthly if you prefer (some businesses do for cashflow visibility), but you cannot elect annual unless you remain voluntarily registered below $75k turnover.
When is the next quarterly BAS due?
Q1 (Jul-Sep) is due 28 October. Q2 (Oct-Dec) is due 28 February. Q3 (Jan-Mar) is due 28 April. Q4 (Apr-Jun) is due 28 July. When the 28th falls on a weekend or public holiday, the deadline shifts to the next business day. Lodging through a registered BAS or tax agent typically adds a one-month extension to Q1, Q3 and Q4 (Q2 has no extension).
Why is the Q2 BAS due 28 February — that is more than 28 days?
Q2 covers October to December and lands across the Christmas closedown period. The ATO recognises this and built the longer 59-day window directly into the standard self-lodger date — which is why a BAS agent extension does not apply to Q2. Every other quarter has 28 days; Q2 effectively has its extension already baked in.
What happens if I lodge or pay late?
Failure to lodge on time (FTL) penalty is 1 penalty unit per 28 days late, capped at 5 penalty units for a small entity ($1,565 at the current penalty unit rate of $313). General interest charge (GIC) applies to unpaid GST and PAYG. The ATO can also waive the FTL penalty if it is your first time and you lodge within a reasonable window — call them as soon as you know you will be late.
Can I switch from quarterly to monthly?
Yes. You can elect monthly at any time through ATO online services or through your tax agent. The change is straightforward and takes effect from the start of the next BAS period. Returning to quarterly requires an ATO election in writing and is normally limited to those with turnover under $20 million.
Do I lodge a BAS or an IAS?
You lodge a BAS if you are registered for GST. You lodge an IAS (Instalment Activity Statement) if you have PAYG withholding or PAYG instalment obligations but are NOT registered for GST. Many small businesses lodge an IAS for the first six to twelve months while building up to the $75k GST threshold, then switch to BAS on GST registration.
What needs to be on a BAS?
The labels you complete depend on what you are registered for. GST: G1 (total sales), G2/G3 (GST-free sales), G10/G11 (purchases), 1A (GST on sales), 1B (GST on purchases). PAYG withholding: W1 (gross wages), W2 (PAYG withheld). PAYG instalments: T1/T2/T7. Fuel tax credits: 7C/7D. WET, LCT and other smaller labels apply only if registered for those obligations.
Can I use software to prepare my BAS?
Yes — Xero, MYOB, QuickBooks and most major accounting platforms automatically compile a draft BAS from your transaction history. You then review against any cash-basis adjustments, period cut-offs and one-off items, and lodge through ATO online services or via your registered BAS or tax agent's portal.
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