Shadow assistant treasurer Andrew Leigh has blamed problems with the Australia Tax Office's (ATO) online tax lodgement system on job cuts in the public service.

Since last week, people trying to file their tax returns through ATO's online system have faced delays and technical issues.

Mr Leigh told ABC News Radio that the ATO staff were being asked by the Government to deliver the new myTax System, while the tried and tested eTax system was being phased out.

He said the Federal Government expected its agencies to roll out new systems, while slashing public service jobs - and the online tax lodgement problems were just more evidence that such job cuts ultimately impacted on everyday Australians.

"It's just another example of how short-sighted public service cuts end up affecting people," he said.

"They don't just affect public servants, the 4,700 people who've lost their jobs, but they end up affecting the millions of Australians that will be looking to file their tax returns over the course of the coming months."

'We suggest that you wait until August'

Mr Leigh said the ATO had an IT system that seemed to be struggling to keep up.

"I don't blame the Tax Office. I blame a Government which expects agencies to roll out new systems while slashing the public service," he said.

According to the Community and Public Sector Union (CPSU), more than 17,000 public sector jobs have been cut by the current Federal Government since it took office.

ATO Second Commissioner Geoff Leeper apologised for the technical issues.

"We're sorry for any inconvenience that issues with our online systems have caused ... our online experience for people is better today than yesterday (Tuesday)," he said.

"Further enhancements and improvements to our systems are continuing. As at midday today our data is showing us that 90 per cent of taxpayers trying to lodge are successfully accessing online services and lodging their returns."

However, Mr Leeper said he was disappointed that some people were still experiencing some slowness.

"You've told us we have a great product in myTax. People that are successfully lodging are telling us how quick and easy it is," he said.

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The commissioner said the number of lodgements to date was on par with last year.

"We've already received nearly 300,000 tax returns, including nearly 120,000 through myTax (71,000) and eTax (47,000) as at July 7," he said.

He suggested customers waited until August to lodge their returns, if possible.

"If it's not urgent for you to lodge now, we suggest that you wait until August when there will be more pre-fill data available," he said.

The ATO told customers via Twitter on Tuesday that their number one priority was to fix the online services, asking customers to be patient.

On social media, many users are now reporting success with the filing of their returns.

"Finally got to lodge mine this morning. Thank you for finally starting to get on top of this issue," said one user on Facebook.

"YAY!!!! Just lodged and the system worked perfectly ... much easier than last year - u have done a great job !! am very happy," another user said.

But other users are still reporting difficulties.

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