ATO default assessment: how to fix an estimated tax bill
If you have not lodged tax returns or BAS, the tax office can estimate what you owe and send you a bill. This is called a default assessment, and the estimate is often higher than your real tax.
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Time limits apply. There are strict time limits to challenge a default assessment, and the debt can be collected in the meantime. Call 0466 268 405 now.
What is a default assessment?
A default assessment is a tax bill the tax office works out using the information it has – for example data from banks, employers, other businesses or past returns – when you have not lodged. It can cover income tax, GST or other amounts.
Why the bill is often too high
- It may not include your business expenses or deductions
- It may count income twice or include money that is not income
- It may not include tax credits, PAYG withheld or GST credits
- Penalties and interest are usually added on top
How to fix it
- Gather your records. Bank statements, invoices, receipts and payroll details.
- Prepare the correct returns or BAS. We prepare accurate figures for every period involved.
- Challenge the assessment. Usually this is done by lodging the correct figures and, where needed, a formal objection within the time limit. You must show the estimate is wrong, so good records matter.
- Deal with the debt. Ask about penalty remission and a payment plan for whatever is really owed.
Good to know: A default assessment is still a real debt until it is changed. Recovery action can continue while it is being reviewed, so it is important to act quickly.
How UV TAX can help
- Prepare overdue tax returns and BAS from your records
- Compare our figures with the default assessment
- Lodge the correct figures and any objection needed
- Request penalty remission where there are good reasons
- Arrange a payment plan for what is really owed
⚠️ General information only – not tax or legal advice. UV TAX is a registered tax agent, not a law firm, and cannot give legal advice. Where legal advice is needed we will tell you so you can speak with a lawyer. The tax office decides whether an assessment is changed. Strict time limits apply to objections. This page is a simple overview as at November 2026 and does not consider your personal circumstances. Laws, rates and thresholds change, and outcomes are decided by the tax office or the courts – UV TAX cannot guarantee any result. Please get advice for your situation before acting.
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0466 268 405Frequently asked questions
What is an ATO default assessment?
It is a tax bill the tax office estimates when you have not lodged returns or BAS, using the information it already has.
Is a default assessment final?
No, but it is a real debt until it is changed. You can usually challenge it by lodging the correct figures and objecting within the time limit.
Why is my default assessment so high?
It often leaves out your expenses, deductions and credits, and penalties and interest are usually added.
Can the tax office collect the debt while I challenge it?
Yes, recovery action can continue, which is why it is important to act quickly and talk about a payment arrangement.
How long does it take to fix?
It depends on how many periods are involved and how good your records are. We can usually start straight away.
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General information current as at November 2026.