Your 2026 BAS Calendar: Every Quarterly Deadline (and How to Never Miss One)

Every quarterly deadline for the rest of 2026, what each BAS actually covers, and the simple habits that stop lodgement day from turning into a scramble.

If you’ve ever found yourself digging through a shoebox of receipts on the 27th of the month with a BAS due the next day, you’re not alone. Most Australian small businesses lodge quarterly, and the same four dates roll around every year — but somehow they still catch people out. This calendar lays out exactly when each 2026 BAS is due, what’s included, and how to build a system so lodgement day stops being a fire drill.

"2026 calendar with quarterly BAS lodgement deadlines marked for an Australian small business"

What a BAS actually covers

A Business Activity Statement reports GST collected and paid, PAYG withholding from staff wages, and — where applicable — PAYG income tax instalments. For most small businesses registered for GST, it’s the single most important recurring compliance task in the calendar, because it ties together sales, expenses, and payroll into one lodgement.

Most businesses with a GST turnover under $20 million lodge quarterly. Above that threshold, monthly lodgement is compulsory, with each BAS due on the 21st of the following month.

The 2026 quarterly BAS deadlines

Here’s every quarterly due date left in the 2026 calendar year, covering the tail end of the 2025–26 financial year and the start of 2026–27.

  • Q3 (January–March 2026): due 28 April 2026 — 26 May 2026 if lodged through a registered BAS or tax agent
  • Q4 (April–June 2026): due 28 July 2026 — 25 August 2026 through a registered agent
  • Q1 2026–27 (July–September 2026): due 28 October 2026 — typically an extra two weeks through a registered agent
  • Q2 2026–27 (October–December 2026): due 28 February 2027, with no further agent extension, since this date already includes a built-in one-month concession over the Christmas and New Year period

If any due date falls on a weekend or public holiday, the ATO automatically shifts it to the next business day. Worth noting: agent concessions only apply if you’re registered with that agent before the standard due date and your previous lodgements are up to date — it isn’t something you can claim retroactively once you’re already late.

Why these dates keep catching businesses out

In our experience working with small businesses across the Hills District, missed or rushed BAS lodgements almost always trace back to the same three habits, not a lack of knowing the date.

  1. Reconciliation is left until the deadline is close. Three months of unreconciled transactions is a very different job to a five-minute weekly check.
  2. GST coding errors pile up unnoticed. A handful of miscoded invoices in month one become a much bigger correction job by month three.
  3. Cash isn’t set aside as GST is collected. The BAS bill feels like a surprise because the money was never separated from everyday trading funds in the first place.
"Small business owner checking GST and BAS figures in Xero ahead of a quarterly lodgement deadline"

A simple system to never miss a deadline again

None of this requires new software or a major process overhaul — just a few consistent habits built around the dates above.

  • Put all four dates in your calendar now, with a reminder set 10–14 days out, not the day before.
  • Reconcile weekly, even if it’s a short session, so BAS prep is a review rather than a rebuild.
  • Set aside GST as you go, ideally into a separate account, so the BAS payment is never a cash flow shock.
  • Run a mid-quarter GST check, roughly six weeks into each quarter, to catch coding errors while they’re still a quick fix.
  • Register with a BAS agent before the standard due date if you want the benefit of the lodgement extension — it isn’t available after the fact.

When it's worth handing BAS over to someone else

Plenty of business owners manage their own BAS lodgements without issue, particularly in the early stages. The point where it’s usually worth bringing in a bookkeeper is when turnover grows, staff are added to the payroll, or BAS prep starts eating into the time that should be spent running the business. At that stage, a bookkeeper who already has the calendar, the coding, and the reconciliation habits in place tends to save far more time than the service costs.

Frequently Asked Questions

When is the next BAS due in 2026?

The next quarterly BAS covers April–June 2026 and is due 28 July 2026 if you lodge yourself, or 25 August 2026 if a registered BAS or tax agent lodges on your behalf.

The ATO automatically moves the deadline to the next business day, so no separate action is needed — the standard rule applies to both lodgement and payment.

Generally yes, provided you’re registered as their client before the standard due date and your previous lodgements are up to date. The concession is usually a few extra weeks, though the December quarter’s concession is already built into its standard 28 February due date.

The ATO can apply a Failure to Lodge penalty, charged in 28-day blocks, plus the General Interest Charge on any amount still owing — both of which are avoidable with a reminder system and a bit of planning ahead.