Common ATO Tax Return Mistakes That Delay Your Refund (2025-26)

1. Lodging too early, before your pre-fill is ready

Lodgement opens on 1 July, but your employer, banks and health fund have not finished reporting to the ATO yet. Until your income statement shows "Tax ready" (usually by late July), the pre-filled figures can still change. Lodge on top of "not tax ready" data and you may have to amend later — which is slower than just waiting a few weeks in the first place. Fix: wait until late July, when your pre-fill is complete.

2. Leaving out income the ATO already knows about

This is the single most common cause of a held-up refund. The ATO data-matches your return against reports it already receives, so missing income creates an instant mismatch. The usual culprits:

• Bank interest — even a few dollars from a savings account is reported
• A second job — every employer reports your pay
• Dividends and managed-fund distributions
• Gig and platform income — ride-share, delivery, freelancing and marketplaces increasingly report to the ATO
• Some government payments that are taxable

Fix: check every pre-filled figure is present and add anything missing. If the income is genuinely yours, declaring it is not optional — and you can usually claim the expenses that go with it.

3. Over-claiming or guessing your deductions

Deductions are where refunds are made, but they are also the ATO's main focus. The errors that draw attention are:

• Double-dipping on working from home — claiming the 70c-per-hour fixed rate and a separate phone or internet bill. The rate already includes them.
• Round-number estimates — "$1,000 of work expenses" with no records behind it.
• Claiming private costs — commuting from home to work, plain clothes, or coffee at the office are not deductible.
• Copying last year — reusing last year's figures instead of this year's actual spending.

Fix: claim what you actually spent, keep a receipt or record for each item, and make sure you are using the right method. Under-claiming is just as costly in the other direction — many people leave legitimate deductions on the table.

4. Wrong or outdated bank account details

Your refund is paid to the account you nominate. If those details are old or wrong, the payment can fail or bounce, adding weeks of delay while it is sorted out. Fix: confirm your bank details on the final screen before you submit.

5. Forgetting capital gains and crypto

Selling shares, property or cryptocurrency during the year can trigger a capital gain that must be declared. Crypto in particular is often forgotten, but exchanges report to the ATO and a missing gain is a common mismatch. Fix: include any asset you sold, and remember the 50% CGT discount may apply if you held it for over 12 months.

6. Not reconciling private health and Medicare

Your private health insurance details feed the private health rebate and the Medicare levy surcharge. If they are missing or wrong, your return can be incorrect and held for review. Fix: check your health fund statement is pre-filled correctly before lodging.

7. Expecting a refund when a debt will offset it

This is not strictly a mistake, but it surprises people every year. If you owe money to the ATO, Centrelink or certain other agencies, or a HECS/HELP repayment has fallen due, your refund can be reduced or fully absorbed. Fix: factor in any known debts so the final figure is not a shock.

Get it right the first time

Almost every item above comes down to two habits: match the ATO's data (declare all your income), and back up every deduction (claim what you spent, with a record). A return built that way is the kind the ATO processes quickly and without questions.

This is exactly what EOFYmate's lodge-ready claim report is for: it lists each deduction with the plain-English ATO rule behind it and where it goes on your return, so you can match it against your pre-fill, avoid both over- and under-claiming, and type the figures into myTax with confidence.