The Federal Government’s ability to run a tech service has not improved over the New Year break.

Centrelink has been slammed in recent days after hundreds of Australians claimed they were issued large debt notices for amounts they did now owe.

Centrelink’s “automated debt recovery system” issued letters in December last year calling for the repayment of “debt” from $800 to over $25,000

The automated system has been accused of miscalculating bills and sending debt notices to people who do not owe, with mounting reports of Australians – including asylum seekers and people with disabilities – being sent inaccurate debt notices.

The new compliance system matche data froms Centrelink's income information with other government records, including at the Australian Taxation Office.

Centrelink says it is “confident in the online compliance system, and associated checking process that we go through with recipients”.

“The online compliance intervention system doesn’t automate debt recovery – it is a system which automates part of the standard compliance review process,” the agency said in a statement.

“While the new online compliance system automates part of this process, it does not change how income is assessed or how debts are calculated - it is an easy way to confirm details and resolve any outstanding matters.

“When data differences are detected, the system generates a letter (this is not a debt letter) advising people of the difference and asking them to either confirm or update their details online using myGov. These are not debt letters and at this stage of the process no debt has been raised.”

It said 72 percent of people who received online compliance letters since September 2016 were able to resolved the matter.

“Only 2.2 per cent of customers were requested to supply supporting documentation, which means 97.8 per cent of customers did not need to supply supporting documentation,” the statement said.

“The department is determined to ensure that people get what they are entitled to, nothing more, nothing less.”

Opposition leader Bill Shorten said; “This farce has to end”.

“This stuff-up has delivered a summer from hell for thousands of people who have done absolutely nothing wrong,” he told Fairfax.

Social Services Minister Christian Porter has defended the system, saying it has already returned $300 million to the taxpayer

“From what we've seen in a high-volume system, it's actually working incredibly well,” he said.