The Australian Tax Office's digital services went offline for just over three hours this morning in the second major outage to hit the government agency in a week.
Users started complaining at around 8am Friday morning that the main ATO website was returning a "A701.11 unexpected error" message.
The ATO later changed the landing page to advise that the website was unavailable.
"We apologise for the inconvenience and assure you of our commitment to provide you with the best possible experience of using our online services," it read.
"We thank you for your patience as we work to restore our services."
The ATO said it was investigating the system issues "as a priority".
It was unable to provide a timeframe for service restoration, but at around 11:25am advised that its systems were back up and running.
"Thanks for your patience. Some functionality is limited as a result of recent system outages."
The agency was still grappling with the fallout from last week's outage at the time today's systems issues arose.
It had not yet managed to fully rectify its systems: the practitioner lodgment service was yet to be restored, while the Australian Business Register had been brought back online, but with reduced functionality.
The ATO's online presence, as well as its internal Siebel and Sharepoint systems, went down on Monday following the collapse of an HPE storage network.
Data corruption issues from its primary HPE SAN were replicated onto its secondary SAN, leaving it scrambling to restore 1PB of storage capacity from back-up.
It was able to bring its main website back online on Tuesday night, and other core services subsequently over the following few days.
Last Friday the ATO pledged to undertake an independent review into the storage network crash behind last week's outage.
It labelled the IT disaster its "worst unplanned outage" in recent memory.
More to come