what happens if i don't lodge my tax return by 31 october

June 27, 2026

If you don’t lodge your Australian tax return by 31 October, it’s treated as late, and you can be hit with escalating penalties, interest on any tax owed, and a higher risk of ATO enforcement or audit. The sooner you lodge or contact the ATO or a tax agent, the more likely you are to minimise or avoid these consequences.

Quick Scoop

31 October is the standard ATO deadline for individual tax returns if you’re not on a registered tax agent’s lodgement list.

Missing it can trigger a Failure to Lodge (FTL) penalty, generally starting at around $330 once you’re overdue, then increasing every 28 days up to a typical cap of about $1,650 for individuals.

Penalties can apply even if you’re due a refund, and interest can build on any unpaid tax.

In more serious or long‑term non‑lodgement cases, the ATO can issue default assessments, pursue debt recovery, or even prosecute.

What exactly happens after 31 October?

Once 31 October passes and you haven’t lodged (and you’re not covered by a tax agent extension), your return is simply considered late.

The ATO can record a failure to lodge on time and may start by sending reminder letters, myGov notifications, or SMS nudges.

If you still don’t act, they can formally apply a Failure to Lodge (FTL) penalty and may flag your account for closer review.

If you register with a tax agent before 31 October, you’re usually moved to the tax agent lodgement program, which often gives a later due date, so “late” is then judged against that extended deadline instead.

Penalties and interest: how they work

The FTL penalty is calculated using penalty units and time overdue.

For individuals, many tax specialists describe the practical outcome as about $330 per 28‑day period (or part thereof) that the return is late, up to a maximum of around $1,650 (five periods).

The penalty can start once you’re just one day overdue, even if you ultimately get a refund, because the obligation is to lodge, not only to pay.

If you owe tax:

The ATO can add General Interest Charge (GIC) on unpaid amounts for each day they remain outstanding.

That interest is on top of any late‑lodgement penalty, so delaying can get much more expensive over time.

In more persistent cases of ignoring obligations, tax law also allows for prosecution, with courts able to impose higher fines and, in rare situations, short terms of imprisonment.

Other risks: audits, default assessments, and your record

Late lodgement doesn’t automatically mean an audit, but it does increase your risk profile.

Some tax firms note that consistently late or non‑lodged returns are more likely to attract ATO reviews or audits because the ATO sees a pattern of non‑compliance.

If you don’t lodge at all, the ATO can issue a default assessment based on data it already has (for example, income reported by employers, banks, or government agencies), and then chase that amount as a debt.

Your lodgement history matters:

A track record of on‑time lodgements can help when you ask for leniency.
A history of ignoring deadlines makes the ATO less likely to remit penalties.

What you should do if you’ve missed it

If you’ve already gone past 31 October, the key is to act rather than avoid it.

Lodge as soon as you can
- Many online services and tax agents emphasise that lodging quickly is the most effective way to limit penalties because the fine grows with each 28‑day period.

Contact a registered tax agent
- A tax agent can often get you onto their extended lodgement program and help you deal with any outstanding years, penalty notices, or ATO questions.

If you can’t pay, still lodge
- Lodging and then setting up a payment plan with the ATO generally leads to a better outcome than not lodging at all, which is what triggers the nastiest consequences.

Ask for penalty remission if you had a good reason
- Serious illness, natural disasters, or other significant events can sometimes qualify as “special circumstances” and support a request to have penalties reduced or cancelled.

Information gathered from public forums or data available on the internet and portrayed here.