Miss an ATO date and you do not just pay late — you cop a failure-to-lodge penalty and interest on top. The trap in construction is that the deadlines look similar but are not: super for the December quarter is due a full month before the BAS for the same quarter. Here is the calendar, the agent extension, and the penalties.
The quarterly cycle (2025–26)
For a typical small sole trader on quarterly BAS and PAYG instalments:
| Quarter | BAS + PAYG-I due | SG due (if you employ) |
|---|---|---|
| Jul–Sep | 28 October | 28 October |
| Oct–Dec | 28 February | 28 January |
| Jan–Mar | 28 April | 28 April |
| Apr–Jun | 28 July | 28 July |
PAYG instalments sit on the same quarterly activity statement, so they line up with the BAS.
The trap: SG and BAS diverge in the December quarter
Three of the four quarters, SG and BAS share a due date. The December quarter is the exception: SG is due 28 January, but the BAS is due 28 February (the December-quarter BAS gets an extra month; SG does not). Pay the December-quarter super on the BAS date and you are a month late — which means lodging an SGC statement and paying the punitive charge. Lock 28 January in separately.
TPAR and income tax
- TPAR (the Taxable Payments Annual Report — mandatory for building and construction businesses paying contractors) is due 28 August after the financial year. For 2025–26, that is 28 August 2026. (See TPAR Explained.)
- Income tax return — self-lodger: 31 October after year-end (31 October 2026 for 2025–26).
The tax-agent extension
Being on a registered tax agent's client list buys you a later lodgement date — you just have to be on their list by 31 October, not lodge by then:
- 31 October — if you have a prior-year return outstanding at 30 June, or the agent is advised of this date.
- 31 March — if your latest return had tax payable of $20,000 or more.
- 15 May — "all remaining" individuals and trusts (most sole traders).
- 5 June concession — a 15 May return lodged and assessed by 5 June can have payment due 5 June (depends on assessment timing).
Payment usually aligns with the lodgement due date — but interest runs if you pay late even when you have lodged on time.
Payday Super changes the SG calendar from 1 July 2026
The quarterly SG dates above apply to quarters ending on or before 30 June 2026. From 1 July 2026, Payday Super requires SG to be paid with each payday (reaching the fund within about 7 business days of each pay event) — so the quarterly SG schedule is superseded for 2026–27 onwards. BAS, TPAR and income-tax dates keep their usual patterns.
Failure-to-lodge (FTL) penalties
Lodge late and the FTL penalty applies — 1 penalty unit per 28 days (or part) overdue, capped at 5 units. For a small entity (a penalty unit is around $330 in 2025–26):
- 1–28 days late: 1 unit (~$330)
- 29–56 days: 2 units (~$660)
- 57–84 days: 3 units (~$990)
- 85–112 days: 4 units (~$1,320)
- 113+ days: 5 units (~$1,650) — the cap
It applies to activity statements, income tax returns, PAYG withholding annual reports, TPAR and FBT/annual GST reports — and it is separate from the general interest charge (GIC) that runs on late payment until you pay.
Commonly missed dates
- Q4 BAS + PAYG (28 July) — lands in the EOFY cash pinch.
- TPAR (28 August) — subbie-heavy businesses often do not realise it is mandatory.
- Q2 SG (28 January) — post-Christmas, and a month before the matching BAS.
- 31 October income tax — if you did not get onto an agent's list in time.
Common mistakes
- Paying December-quarter super on the BAS date (a month late).
- Assuming the agent extension means "lodge whenever" — you must be on the list by 31 October.
- Forgetting GIC runs on late payment even when you lodged on time.
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