BAS deadlines depend on how often you lodge — monthly, quarterly, or annually. For most small businesses, quarterly BAS is due 28 days after the end of each quarter. Lodging late triggers an ATO Failure to Lodge (FTL) penalty, and paying late attracts the General Interest Charge (GIC). Acting early — even if you cannot pay in full — is always better than ignoring the obligation.
Quarterly BAS Due Dates (FY2025–26)
| Quarter | Period | Due date (self-lodgers) |
|---|---|---|
| Q1 | 1 July – 30 September 2025 | 28 October 2025 |
| Q2 | 1 October – 31 December 2025 | 28 February 2026* |
| Q3 | 1 January – 31 March 2026 | 28 April 2026 |
| Q4 | 1 April – 30 June 2026 | 28 July 2026 |
*The December quarter deadline is extended to 28 February to account for the summer holiday period.
BAS agent extended deadlines: If your BAS is lodged by a registered BAS agent, extended lodgement dates apply — typically 25 days beyond the standard deadline for businesses on a BAS agent lodgement program. Confirm the exact dates with your agent.
Monthly BAS Due Dates
Monthly BAS is mandatory for businesses with GST turnover of $20 million or more. Monthly BAS is due on the 21st of the following month.
| Month of activity | Due date |
|---|---|
| July 2025 | 21 August 2025 |
| August 2025 | 22 September 2025 |
| September 2025 | 21 October 2025 |
| And so on… | 21st of the following month |
Annual BAS Due Dates
Eligible businesses with GST turnover under $75,000 who lodge annually have their BAS due 31 October following the end of the financial year (the same as the individual income tax return deadline).
- Annual BAS for FY2024–25: due 31 October 2025
However, annual lodgers may still be required to pay GST instalments quarterly during the year (the ATO notifies you of the instalment amount). The annual BAS reconciles the actual GST against instalments already paid.
Penalty for Late Lodgement — Failure to Lodge (FTL)
If you do not lodge your BAS by the due date, the ATO will impose a Failure to Lodge (FTL) penalty. The penalty accrues in blocks of 28 days.
| Entity size | Penalty per 28-day period | Maximum (5 periods) |
|---|---|---|
| Small business (under $1M turnover) | 1 penalty unit = $330 | $1,650 |
| Medium business ($1M–$20M turnover) | 2 penalty units = $660 | $3,300 |
| Large business (over $20M turnover) | 5 penalty units = $1,650 | $8,250 |
Penalty unit value is indexed periodically. As at FY2025–26, one penalty unit = $330.
The penalty applies even if the net GST for the period is zero (a “nil BAS”). Lodging a nil BAS late still attracts FTL.
First-Time Leniency
The ATO has discretion to remit FTL penalties in full or in part. For a first-time or isolated lodgement failure with no prior history, the ATO will often remit the penalty if you contact them and lodge promptly. The ATO is less lenient with repeat offenders.
Penalty for Late Payment — General Interest Charge (GIC)
If you lodge on time but pay late, the ATO applies the General Interest Charge (GIC) on the outstanding amount. The GIC rate is updated quarterly and is significantly higher than commercial interest rates.
- As a guide, the GIC rate for Q2 FY2025–26 was approximately 11.38% per annum (compounded daily)
Interest accrues from the day after the due date until the amount is paid.
What to Do If You Can’t Pay on Time
The ATO strongly prefers that you lodge on time even if you cannot pay. Lodging stops the FTL penalty from accruing. Then contact the ATO to arrange a payment plan:
- Call the ATO Business line on 13 28 66
- Arrange a payment plan online via the ATO Business Portal or myGov
- Provide realistic payment terms — the ATO typically accommodates genuine cash flow difficulties
A payment plan does not remove the GIC, but it does stop further FTL penalties and prevents the ATO from taking debt recovery action while you are complying.
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Frequently Asked Questions
Is the BAS deadline different for companies and sole traders? No — the lodgement deadline (28 days after quarter end, or the 21st for monthly) applies to all entity types equally. The only exception is BAS lodgements made through a registered BAS agent, which may receive extended dates.
What if my due date falls on a weekend or public holiday? If the due date falls on a Saturday, Sunday, or public holiday, the deadline moves to the next business day.
Can the ATO charge both FTL penalties and GIC at the same time? Yes. FTL applies to late lodgement, GIC applies to late payment. You can be charged both if you lodge and pay late. Lodging on time (even without payment) eliminates the FTL risk.
This article provides general tax information. For advice tailored to your situation, speak with a registered tax agent or BAS agent. Find one through the Tax Practitioners Board register.