ATO Disallowed Your Tax Deductions: What to Do Next

If the ATO disallows a deduction, begin with the exact adjustment in the notice. A claim can fail because the expense was not incurred, the link to earning income was not established, the private portion was not separated or the required records are missing. The reason matters because each problem calls for different evidence.

Why did the ATO disallow the deduction?

Read the ATO's letter and the original and amended assessments together. List each changed item, tax year, amount and reason given. A receipt can establish that money was spent, but it does not by itself establish that an expense is deductible. For employee work expenses, the ATO says you generally need to show that you paid the expense without reimbursement, it directly relates to earning your income and you have a record to prove it. If an item served both work and private purposes, only the work-related part may be claimable.

Different deductions can have different rules. Travel, car expenses, working from home, self-education and business expenses may each call for particular records or calculations. Check the rules that applied to the tax year under review, rather than assuming today's method applied in an earlier year.

What evidence should you gather?

Match evidence to the ATO's actual reason for removing each claim. Useful material may include supplier invoices, receipts, bank entries, employer records, diary entries, rosters, logbooks, contracts and working papers. A bank statement can help show a payment, but it may not establish the nature of the item or its work-related use on its own.

1. Keep the ATO notice, original return, amended assessment and any audit or review correspondence.
2. Identify the expense, date, amount and person who paid it.
3. Explain how the expense helped earn the relevant income, supported by records from that time.
4. Calculate any private portion or reimbursement and retain the method used.
5. Reconcile the supported total to the amount claimed in the return.

When a matter concerns an older tax year, some records may be hard to locate. Ask suppliers, employers, banks or other record holders for copies where possible. Reconstruct calculations from reliable surviving material and explain any gaps honestly. Do not replace missing evidence with an unsupported estimate.

Check the tax, penalty and interest separately

The removed deduction may increase taxable income and the tax assessed. A penalty or interest charge may also appear, but each has its own basis. Check the assessment calculation, the penalty decision and the interest entries separately. Correcting the underlying claim does not automatically resolve every other component.

If the ATO's adjustment is wrong, an objection may be the formal route to challenge an amended assessment. The applicable time limit depends on the decision and circumstances. Read the review-rights section of the notice and the ATO's current guidance immediately. A discussion with the ATO does not necessarily preserve an objection deadline. Our ATO objection guide explains how to prepare grounds, calculations and evidence.

What if the ATO is right about part of the claim?

A useful review can separate supported deductions from claims that should be reduced or withdrawn. The goal is the correct tax position, not to defend every original figure. If some items were partly private or reimbursed, update the calculation. If you disagree only with another item, identify that item clearly and support the result you seek.

Watch our short video, ATO disallowed your tax deductions?, for the central questions to ask before responding. If the amended bill is large, our large ATO tax bill video explains why tax, penalty and interest may require separate attention.