Fixing a tax return: amendments, objections, tribunal review and complaints

If you find a mistake in a return that has already been assessed, you amend it, usually online in myTax through ATO online services or through your tax agent. Most individuals can amend within two years of the date on their notice of assessment; the period is four years for people with more complex affairs. If you disagree with an ATO decision, such as an amended assessment or a penalty, you lodge an objection, generally within the same two- or four-year period (shorter for some decisions). If the objection is disallowed, you can apply to the Administrative Review Tribunal (ART), which replaced the Administrative Appeals Tribunal in October 2024, or appeal to the Federal Court. Complaints about how the ATO treated you go first to the ATO, then to the Inspector-General of Taxation and Taxation Ombudsman.

This guide explains each route, when to use it and what to prepare. It is general information; for disputes involving significant amounts, consider a registered tax agent or a lawyer.

Amending your own return

Situation	What to do
You left out income or over-claimed a deduction	Amend to correct it; pay the extra tax and any shortfall interest
You forgot a deduction or offset	Amend to claim it within the review period
A late statement (ETF, private health) changes figures	Amend with the updated figures
The ATO has already adjusted your return	Check its letter; you may need to object rather than amend

How: in myTax, choose the year, select amend, change the relevant labels and submit. Paper amendment requests are still possible. Keep a note explaining what changed and why.

Effect: the ATO issues a notice of amended assessment. If you owe more, shortfall interest charge generally applies from the original due date, and the general interest charge applies if you don't pay by the new due date. If you correct an error before the ATO starts an examination, any shortfall penalty is typically reduced substantially, and often not applied for honest mistakes.

The review periods

Period	Who it usually applies to
2 years from the notice of assessment	Most individuals whose affairs are simple, including employees and many investors
4 years	Individuals with more complex affairs, for example certain business income or arrangements, or interests in some trusts
Unlimited	Where the ATO considers there has been fraud or evasion

Exact eligibility for the shorter period is set out in the Income Tax Assessment Act 1936 (section 170) and the ATO's guidance. If you are not sure which applies, act as if you have two years.

Objecting to an ATO decision

An objection is a formal challenge. Use it when the ATO has made a decision you think is wrong, for example:

an amended assessment after an audit or review;
a decision to deny a deduction or apply a penalty;
certain decisions about super contributions or private rulings (some have a 60-day limit).

Steps:

Lodge the objection online, by your agent or in writing, within the time limit.
State fully and in detail the grounds: what decision, why it is wrong, what the correct outcome is.
Attach evidence: receipts, logbooks, contracts, bank records.
The ATO reviews it with an officer who was not involved in the original decision and issues an objection decision.

If you miss the deadline, you can ask for an extension of time with reasons; it is not automatic.

The ATO also offers in-house facilitation, a free mediation-style process, for some disputes.

External review

If your objection is disallowed in whole or part:

Route	Features
Administrative Review Tribunal	Reviews the merits of the decision afresh; an application fee generally applies, with reductions in some cases; less formal than court
Federal Court of Australia	Appeal on the law; more formal and costly; legal representation advisable

Time limits to apply are short (generally 60 days from the objection decision for the ART). Check the ART website for current fees and forms.

Lodging an objection or review does not usually stop the debt being payable. Talk to the ATO about payment arrangements while the dispute is resolved.

Complaints about service or conduct

Complaints are different from disputes about the amount of tax. Use them for delays, poor communication, privacy concerns or unfair treatment.

ATO complaints: online, by phone or in writing. Give your reference numbers and what outcome you want.
Inspector-General of Taxation and Taxation Ombudsman (IGTO): independent, free; usually you should first give the ATO a chance to resolve the complaint.
Tax Practitioners Board: for complaints about a registered tax or BAS agent's conduct, or unregistered people charging for tax services.
Office of the Australian Information Commissioner: for privacy concerns not resolved by the ATO.

Worked scenario

Illustrative: in September 2026 Chris realises his 2024–25 return (assessed in August 2025) omitted $3,000 of ETF distributions. His affairs are simple, so the two-year period runs to August 2027.

He amends in myTax. Extra tax at 32% ≈ $960.
Shortfall interest applies from the original due date to the amended notice: a modest amount.
Because he corrected it before any ATO contact and the error was an oversight, a penalty is unlikely.
Had he waited until the ATO's data matching flagged it, the same tax and interest would apply, with a greater chance of a penalty.

FAQ

Should I amend or object?

Amend your own return to correct your own errors. Object when you disagree with a decision the ATO has made.

Can I amend to claim a deduction I forgot three years ago?

Only if you are still within your review period, which for most individuals is two years from the assessment.

Does the ART charge a fee?

Generally yes, with exemptions or reductions in some circumstances. Check the ART website for the current amount.

What if my tax agent made the error?

You still amend. If the agent failed to take reasonable care, you may be protected from penalties (safe harbour), and you can raise the matter with the agent or the Tax Practitioners Board.

Sources

Australian Taxation Office — amending your return, objections, in-house facilitation, complaints
Administrative Review Tribunal — applying for review of tax decisions
Inspector-General of Taxation and Taxation Ombudsman — complaints about the ATO
Tax Practitioners Board — complaints about tax agents
Office of the Australian Information Commissioner — privacy complaints
Federal Register of Legislation — Taxation Administration Act 1953 Part IVC; Income Tax Assessment Act 1936 section 170