The Australian Taxation Office (ATO) has warned workers that the tax return estimate they received may not be completely accurate. After July 1, taxpayers got a rough idea of whether they would owe money or get a nice cash boost from the government department.

Many took to social media to either complain or rejoice at what they saw on their screens. But the ATO has sent out a public service announcement in case some are confused by differences reflected on their tax return.

"When you lodge your return online (via myTax), you’ll see an estimated refund or payable amount at the end before you submit. But here’s the thing…. it’s just an estimate," the tax office said.

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TikTok was flooded with videos after July 1 of Aussies showing their estimates off.

One was disappointed they would be facing a $3,404.10 ATO debt, while another was surprised they were being offered a $3,442 refund.

But the ATO said there are many reasons why your debt or refund doesn't match the estimate.

Do you have a story? Email stew.perrie@yahooinc.com

Why is my ATO tax estimate different to my return?

The estimate from myTax is built from both the information you provide in your tax return as well as the pre-filled details that come from your employer, bank, and other sources of income.

The ATO said it might find discrepancies in this information, which can change what was originally estimated.

Once your tax return is processed, you'll be sent a notice of assessment, which will show if you have a debt or an amount to be refunded.

Your estimate can also be affected if you lodge your tax return before the pre-fill information has arrived.

A staggering 142,000 people who lodged in the first two weeks of July last year had to lodge amendments, or had their returns investigated and amended by the ATO to fix errors.

This takes more time and may ultimately "delay" any refund you receive.

The ATO revealed the estimate can also differ from the amount you receive or owe because it doesn't take into account any existing credits or debits with the tax office.

If you have debts needing to be paid, the ATO can pinch from your tax refund to wipe the slate clean or reduce what you owe.

Other reasons behind differences between your estimate and what's on your notice of assessment include:

• lodging your tax return late

• over claiming your private health insurance rebate

• making a mistake on your return and the ATO had to correct it

• receiving an employment termination payment

• receiving an Australian superannuation lump sum payment

• having excess concessional and non-concessional superannuation contributions

• being entitled to use your spouse’s unused seniors and pensioners tax offset

• receiving credit for tax paid by a trustee

• being entitled to a government super contribution

• being entitled to a low-income super tax offset

• have information in your tax return requiring complex calculations (like income averaging)