My June quarter BAS was due 28 July — what actually happens if I lodge or pay it late?

The bookkeeping is three weeks behind, the June quarter super had to go out the same week, and the activity statement is still sitting in the list of things to do. Somewhere between hoping it will be fine and assuming it will be expensive, the honest question is a specific one: what actually happens if this one is late? The answer is more forgiving than most people expect on the lodgment side, and less forgiving than most people expect on the payment side.

One date, two obligations

For the April–May–June quarter — quarter 4 of the 2025–26 year — the original due date to lodge and pay a quarterly business activity statement is 28 July. Quarterly is the standard reporting cycle for a business with a GST turnover under $20 million, unless the ATO has told you to report monthly.

The two obligations attached to that date are enforced separately. Lodging late can attract a failure to lodge on time penalty. Paying late attracts interest. One is a fixed amount that steps up on a clock; the other accrues daily on whatever is unpaid. Confusing them is what produces the worst version of this — holding the statement back because the money isn't there, which loses the deadline that was easy to keep and does nothing about the one that costs money.

One small mercy in the rules: where a due date falls on a weekend or public holiday, you have until the next business day. In 2026, 28 July is a Tuesday.

You may already have until 11 August — without asking

If you receive and lodge your quarterly activity statement online, an extra two weeks applies automatically. The ATO's two-week lodgment concession covers the quarters ending 30 September, 31 March and 30 June — quarters 1, 3 and 4 — and moves both lodgment and payment out by a fortnight. For the June 2026 quarter that is 11 August. You don't apply for it: if you qualify, the due date shown on the statement itself has already been updated, which makes the statement the thing to check rather than the calendar.

It doesn't cover everything. Monthly activity statements are excluded, so are quarterly instalment notices (the BAS R, S and T forms), and so are large business clients — broadly, those with annual total income over $10 million, GST turnover of $20 million or more, or annual withholding payments over $1 million.

If a registered tax or BAS agent lodges for you electronically, the date shifts again: quarter 4 of 2025–26 is due 25 August 2026 under the agent lodgment program. That concession isn't unconditional — it applies to statements that generate after the previous one was lodged electronically, so a first-ever statement, or one where the last was lodged on paper, can fall back to the earlier date. That is worth a message to your agent rather than an assumption.

What lodging late actually costs

The failure to lodge on time penalty is not a daily meter. It is one penalty unit for every 28 days, or part of 28 days, that the document is overdue, capped at five units. Individuals and small withholders are charged at that base rate; medium withholders are multiplied by two and large withholders by five. A penalty unit is $364 where the infringement occurred on or after 1 July 2026, up from $330.

Two features of that design matter. Because it accrues in 28-day blocks, one day late and 27 days late cost the same. And because it is capped at five units, the penalty eventually stops growing — the interest on unpaid tax does not.

In practice the ATO leaves itself room. It says it generally does not apply penalties in isolated cases of late lodgment, and that where you fail to lodge on time it will warn you by phone or in writing and issue a notice to lodge before a penalty is applied. It also says it will generally not issue an FTL penalty notice for a late-lodged activity statement where the lodgment results in a refund or a nil result — with exceptions, including where the penalty had already been applied before you lodged. Whatever it does cost, it isn't deductible: penalties the ATO imposes can't be claimed.

What paying late actually costs

General interest charge applies where an amount remains unpaid after the date it should have been paid, and the rate is set quarterly. For the July to September 2026 quarter it is 11.43% a year, which the ATO converts to a daily rate of 0.03131507%. It runs on the balance, every day, until the debt is cleared — and interest incurred on or after 1 July 2025 is no longer deductible, which we wrote about separately.

That is the arithmetic behind the standard advice: lodge on time even when you can't pay in full. Lodging costs nothing and stops one clock. The ATO's own instruction is to contact it before the due date if you can't lodge or pay in full and on time, and payment arrangements exist for exactly this situation.

Two assumptions worth checking

The first is that a quiet quarter means there is nothing to lodge. A statement that comes out at nil is still a lodgment the ATO expects — its penalty policy is written around late-lodged activity statements that result in a nil result, which tells you the obligation survives a quarter with no sales.

The second is that using an agent transfers the risk. It can, but only under conditions. Safe harbour protects you from an FTL penalty where you provided your registered agent with all the relevant information needed to lodge by the due date, and the agent's failure to lodge was not because they were reckless or intentionally disregarded the tax law. Both limbs have to hold, and you need evidence for the first — which in practice means the date you sent the records, not your memory of having sent them.

This is general information current as at July 2026, not advice about your business. If the June quarter statement is already late, the order that helps is: lodge it, then ask about remission. The ATO expects outstanding documents to be lodged before it will consider remitting a penalty, and it weighs circumstances such as severe illness, a natural disaster or waiting on information from a third party very differently from being on holiday or busy with work. And if the real problem is that the bookkeeping is permanently three weeks behind the deadline, that is a systems question rather than a penalty one — which is the part our companies, trusts and bookkeeping service is built around.