The portal, that provides online access to government services, was launched in May 2013 with predictions it would attract 5 million users within four years.

By June 2016, more than 9 million Australians had actually signed-up, sending internet bills at the Department of Human Service's internet soaring.

But myGov's first four years of operation were not always smooth.

Public anger at myGov's performance reached boiling point in mid-2015 when Fairfax was inundated by irate users of the portal venting their frustration over being consistently locked out of their accounts or denied access to the portal.

But since Prime Minister Malcolm Turnbull called in his Digital Transformation Office to fix the project in early 2016, a steady and significant improvement to myGov's performance has been widely acknowledged.

Now the National Audit Office's report card, published on Tuesday afternoon, has given a generally positive review of the "the effectiveness of the Department of Human Services' implementation of myGov as at November 2016."

The auditors found the department's efforts in developing and running the portal so far had been "largely effective" and that myGov was generally doing what it was supposed to: making interaction between citizens and government quicker, easier and cheaper.

But the auditors' report card on the flagship digital project is not all glowing; the auditors found that myGov's notorious sign-on problems were not sorted out for 21 months while the department of Human Services waited for money to pay for a fix.

Elsewhere the auditors urged Human Services and the Digital Transformation office to work harder to find out what users of the portal were really experiencing.

By November 2016, myGov had almost 11 million user accounts.

Supporting the extra users, and the extra telecoms bills, sent the Department of Human Services scrambling around for money to top-up the originally budgeted $29 million with about $86 million having been spent so far.

The money was found from a pre-approved Human Services contingency fund, top-up funding from the government and from asking other departments using the portal to provide services to put their hands in their pockets.

DHS says myGov has already saved more than $109 million as users of Centrelink, Medicare, the ATO, Child Support and the National Disability Insurance Scheme moving their transactions online.

The auditors were skeptical of this figure, saying there was a danger it might be "overstated", but acknowledged that myGov had been effective in saving money.

Human Services and the Tax Office also predicted in 2014 that myGov would deliver annual "red tape" savings of $93 million to its users each year when it was up and running, although the auditors were unable to test those claims.

The auditors noted DHS had been slow to move fixing the single biggest source of frustration for myGv users: the sign-in process.

"Human Services was aware of the reported issues with the myGov sign-in process since September 2014," the auditors wrote.

"Resolving this issue was reportedly Human Services' top priority, as set out in its Top Ten list of reported issues.

"However, a resolution was not implemented until June 2016—more than 21 months later.

The department told the audit team that it did not have the money to act earlier.