ATO Default Assessment: What It Means and How to Fight Back

A default assessment is the ATO calculating your tax bill for you when you fail to lodge - using the income data it holds, allowing no deductions, and typically adding an administrative penalty of 75% of the tax assessed. It is almost always worse than your true position, and the fix is to lodge the actual return to replace it.

Why default assessments are deliberately harsh

They're an enforcement tool, not an accounting exercise. The ATO takes your known income - employer reports, bank interest, business data from BAS or industry benchmarks - assumes the worst on everything else, and assesses accordingly. No work deductions. No cost-of-sales nuance. Then the 75% penalty lands on top. The harshness is the point: it's designed to make lodging the obviously better option.

The burden of proof flips to you

Once a default assessment issues, you must prove what your taxable income actually was - usually by lodging the real return and, where needed, objecting to the assessment. Deadlines apply to objections, so a default assessment letter should never sit in a drawer.

How TaxNudge dismantles them

We obtain the ATO's basis for the assessment, reconstruct the true return using pre-fill data, bank records and your deduction evidence, lodge it, and pursue remission of the 75% penalty - which is far more achievable when the corrected return is filed promptly and voluntarily. Clients regularly see five-figure default assessments collapse to a fraction, or flip to refunds.

General information only - not personal tax, financial or legal advice. Consider your own circumstances or speak to a registered tax agent. Remission of penalties or interest and payment plans are decisions of the ATO and outcomes can't be guaranteed.