BAS Due Dates 2026-27: Every Deadline for Australian Small Business
Miss a BAS deadline and the ATO starts the clock on penalties and interest — and from 1 July 2026 those penalties got more expensive. This page lists every BAS due date for the 2026-27 financial year, verified against the ATO's published dates, plus the extensions you can claim just by changing how you lodge. Bookmark it, or better, put the dates in your calendar before you leave this page.
If you're not sure what actually goes in a BAS, start with our BAS and GST explainer and come back for the dates.
Quarterly BAS due dates for 2026-27
Most small businesses lodge quarterly. The standard rule: your BAS is due on the 28th day of the month after the quarter ends. But almost nobody should be paying on the standard date, because two concessions push it out.
| Quarter | Period | Standard due date | Lodging online | Through a tax/BAS agent |
|---|---|---|---|---|
| Q1 | Jul–Sep 2026 | 28 Oct 2026 | 11 Nov 2026 | 25 Nov 2026 |
| Q2 | Oct–Dec 2026 | 28 Feb 2027* | 28 Feb 2027* | 28 Feb 2027* |
| Q3 | Jan–Mar 2027 | 28 Apr 2027 | 12 May 2027 | 26 May 2027 |
| Q4 | Apr–Jun 2027 | 28 Jul 2027 | 11 Aug 2027 | 25 Aug 2027 |
*28 February 2027 falls on a Sunday, so the effective deadline is Monday 1 March 2027.
The due date is for both lodging and paying. Lodging on time but paying late still racks up interest.
Why Q2 is the odd one out
The October–December quarter would normally be due 28 January, but the ATO builds in an extra month because of the Christmas shutdown — everyone gets until 28 February. That extension replaces the usual concessions, which is why the online and agent columns show the same date. There's nothing extra to claim on Q2, so don't let the generous-looking deadline lull you: it lands right when January's slow trading has drained the bank account. Plan for it.
The two-week extension for lodging online
If you lodge your quarterly BAS yourself through ATO Online services for business, myGov (sole traders) or SBR-enabled accounting software, you get an automatic two-week extension on quarters 1, 3 and 4. No application, no phone call — the later date simply applies.
That turns 28 October into 11 November, 28 April into 12 May, and 28 July into 11 August. If you're still filling in a paper BAS, this is the easiest fortnight of breathing room you'll ever earn. The extension doesn't apply to monthly BAS or to Q2.
Extra time through a tax or BAS agent
Lodge through a registered tax or BAS agent and their lodgement program gives you roughly four weeks past the standard date on quarters 1, 3 and 4 — 25 November, 26 May and 25 August for 2026-27. Two practical points:
- You need to be on their client list before the deadline. An agent can't claim the concession for someone who walks in the day the BAS is due. Engage them before the standard due date, ideally well before.
- Check they're registered. Only agents registered with the Tax Practitioners Board can legally charge to prepare or lodge your BAS. Search the register at tpb.gov.au.
An agent isn't just about the later date — it's about never having to remember the date at all. If you're weighing it up, our guide to bookkeepers, BAS agents and accountants covers who does what and what they cost.
Monthly BAS due dates
Monthly lodgement is compulsory once GST turnover hits $20 million, and optional below that (some businesses choose it to stay on top of cash flow). Monthly BAS are due on the 21st of the following month, with no two-week online extension.
| BAS period | Due date |
|---|---|
| July 2026 | 21 Aug 2026 |
| August 2026 | 21 Sep 2026 |
| September 2026 | 21 Oct 2026 |
| October 2026 | 23 Nov 2026 (21st is a Saturday) |
| November 2026 | 21 Dec 2026 |
| December 2026 | 21 Jan 2027 |
| January 2027 | 22 Feb 2027 (21st is a Sunday) |
| February 2027 | 22 Mar 2027 (21st is a Sunday) |
| March 2027 | 21 Apr 2027 |
| April 2027 | 21 May 2027 |
| May 2027 | 21 Jun 2027 |
| June 2027 | 21 Jul 2027 |
One exception worth knowing: if your turnover is under $10 million and a registered agent lodges your December BAS electronically, the agent program can push that one out to 21 February — a genuine help over the holiday period.
Annual GST return
If you're voluntarily registered for GST (turnover under $75,000, or $150,000 for non-profits), you can report annually instead. Your annual GST return is due at the same time as your income tax return — 31 October if you self-lodge (for the 2025-26 return that's effectively Monday 2 November 2026, since the 31st is a Saturday), or later if a tax agent lodges for you. Not required to lodge a tax return at all? Then it's due 28 February after the end of the annual tax period.
When a due date falls on a weekend or public holiday
Simple rule: you can lodge and pay on the next business day without penalty. That's already baked into the tables above — it's why Q2 effectively lands on 1 March 2027 and why three of the monthly deadlines shift to a Monday. Public holidays work the same way, but be careful with state-based holidays: the ATO applies the rule to its own business days, so don't assume a local show day buys you time. When in doubt, lodge before the weekend anyway — nothing about the next-business-day rule stops you being early.
PAYG instalments: same dates, mostly
If you pay PAYG income tax instalments quarterly, they're due 28 October, 28 February, 28 April and 28 July — the same standard dates as quarterly BAS. If you lodge a full BAS, your instalment simply rides along on it, extensions included. If you only receive an instalment notice (no GST to report), there's nothing to lodge — just pay by the date on the notice, unless you want to vary the amount, in which case lodge the varied notice by the due date. Annual PAYG instalment payers have a single deadline: 21 October.
What late lodgement actually costs
The failure to lodge (FTL) penalty is charged in 28-day blocks. For a small business, it's one penalty unit for every 28 days (or part thereof) the BAS is overdue, capped at five units. A penalty unit is $364 for offences from 1 July 2026 (as at August 2026 — it was $330 before that), so:
| How late | Penalty (small entity) |
|---|---|
| 1–28 days | $364 |
| 29–56 days | $728 |
| 57–84 days | $1,092 |
| 85–112 days | $1,456 |
| 113+ days | $1,820 (capped) |
Medium entities (turnover $1 million to $20 million) pay double; large entities pay five times. On top of the penalty, any unpaid amount accrues general interest charge — 11.43% a year for the July–September 2026 quarter, compounding daily — and since 1 July 2025 that interest is no longer tax deductible. Late BAS lodgement is genuinely expensive now.
Two things soften the blow. The ATO typically doesn't apply FTL penalties to an isolated late lodgement, especially with a clean history — but that's discretion, not a right. And critically: lodge even if you can't pay. Lodging on time stops the FTL clock, keeps you eligible to set up a payment plan, and keeps the ATO onside. Hiding doesn't. If GST bills keep catching you short, the fix is usually upstream — see our guide to cash flow management.
Never miss a deadline: a system that takes 20 minutes
Deadlines aren't a memory problem, they're a systems problem. Set this up once:
- Calendar-block every date now. Put all four quarterly dates (use your actual dates — online or agent) in your phone with two reminders: two weeks out ("reconcile the quarter") and three days out ("lodge and pay").
- Open a separate GST account. Skim your GST portion (for most services businesses, roughly 9–10% of gross takings) into a sub-account every week. BAS day becomes a transfer, not a scramble.
- Let software do the maths. Modern accounting software codes GST as you go and pre-fills your BAS, turning lodgement day into a 15-minute review instead of a shoebox archaeology dig.
- Set up direct debit or pay early. In Online services you can schedule the payment when you lodge — do it in the same sitting so "I'll pay Friday" never happens.
- Or outsource the whole thing. A BAS agent costs a few hundred dollars a quarter, buys you the latest possible deadlines, and makes missing one their problem to prevent, not yours.
Key takeaways
- Quarterly BAS standard due dates for 2026-27: 28 October, 28 February (effectively 1 March 2027), 28 April and 28 July — but lodge online and quarters 1, 3 and 4 extend two weeks automatically.
- A registered tax or BAS agent stretches those to 25 November 2026, 26 May 2027 and 25 August 2027; Q2 gets no extra time for anyone.
- Monthly BAS are due the 21st of the following month, with no online extension.
- Due date on a weekend or public holiday? The next business day counts as on time.
- Late lodgement costs $364 per 28 days for a small business, capped at $1,820 (as at August 2026), plus non-deductible interest above 11% — lodge on time even if you can't pay in full.
- Beat every deadline with four calendar blocks, a separate GST savings account and a scheduled payment.
Where to get help
- ATO — Due dates for lodging and paying your BAS — the official dates, straight from the source.
- ATO — Failure to lodge on time penalty — how penalties are calculated and when they're remitted.
- Tax Practitioners Board — check any tax or BAS agent is registered before you hand over your books.
- business.gov.au — general small business compliance guidance.
- Your accountant or BAS agent — the cheapest insurance against ever reading a penalty notice.
General information only. This guide doesn't take your personal or business circumstances into account and isn't financial, legal or tax advice. Rates and thresholds change — confirm current figures with ato.gov.au or your accountant before acting.