You can now lodge your tax return for the 2023/24 financial year. Here's why you should wait

The ATO says it's better to wait a few weeks before lodging your return. (ABC News: Daniel Irvine)

While the new financial year may have brought on excitement at the thought of a tax refund, Australians are warned not to rush with lodging their returns.

About 14 million Australians are due to submit their returns in the coming weeks but the Australian Tax Office (ATO) says it's not always best to get in early.

Here's why and when you should jump in.

When can I lodge my tax return?

You can lodge your tax return for the 2023/24 financial year now.

But that doesn't mean you should rush to get it in.

The Australian Tax Office actually recommends waiting a few weeks.

Why is it better to wait?

ATO Assistant Commissioner Rob Thomson said people who lodge in early July are twice as likely to make a mistake on their return.

"There is a much higher chance that your return will be missing important information if you lodge in early July," he said in a statement.

"This is particularly relevant if you are receiving income from multiple sources.

"We see lots of mistakes where people who rush to lodge early have forgotten to include interest from banks, dividend income, payments from government agencies and private health insurance details."

To avoid mistakes like this, the ATO can pre-fill many details for you, but it takes them a few weeks to collect the information.

How do I know when the ATO has finished collecting information?

Your income statement — a summary prepared by your employer of your salary and taxes paid for the year — will be marked as "tax ready".

This will be shown when you log into the ATO's Online Services and begin preparing your tax return.

"Once the information we collect is available, all you need to do is check it and add anything that's missing," Mr Thomson said.

What happens if I've made a mistake on my return?

If you realise you've made a mistake after lodging your return, you can submit a request to have it amended.

This can be done through myGov or the ATO app, by sending a letter or through your tax agent.

When is my tax return due?

If you're lodging the return yourself, you have until October 31.

Going through a tax agent can give you an extended deadline, which can be as late as May 15.

If you take this route, it's important to remember to book your appointment with a tax agent before October 31 — but that doesn't mean you have to see them by then.

What happens if I miss the deadline?

You'll still be able to lodge your return but you may cop a fine of $330.

There will also be a further $330 charge every 28 days the return is overdue.

While these charges are capped, it could end up costing you up to $1,650.

Why is my tax return so low this year?

If you've already logged into the ATO's online services to have a look at your tax refund estimate, you might have been surprised to find it's not as big as past returns have been.

There could be a few reasons for this:

• Your refund could have been offset against other debt you have
• There could be a difference between the details in your tax return and the pre-fill information data
• Your income and deductions are different from last year
• The discontinuation of the low- and middle-income tax offset (LMITO)

In past years, the LMITO gave those earning between $37,000 and $126,000 a benefit of up to $1,080, depending on how much they earned.

That was increased in the 2021/22 financial year, so anyone earning between $48,001 and $90,000 received a $1,500 offset.

But the LMITO expired on June 30, 2022, meaning the tax returns of more than 10 million people shrank last year.

The same goes for this year's refund — if it's feeling skinnier than previous years, the missing LMITO could be to blame.

Why do I owe the ATO money?

Similarly to a low return, there are many reasons why you could find yourself with a bill.

The most likely culprits are that your income pushed you into a higher tax bracket, and the Medicare levy.