The Australian Taxation Office (ATO) is currently experiencing system outages affecting all of its online services, including the ato.gov.au website.
In a statement made on Thursday morning, the ATO apologised and admitted the system issues are impacting the organisation's Tax Agent, Business and BAS Portals, ATO online, the Australian Business Register, Standard Business Reporting, and superannuation online services.
According to the tax office, it is in the process of replacing hardware that was affected as a result of the "world first" hardware issue the ATO experienced in December.
"We are replacing the affected hardware, but this process will take some time," the ATO said on Thursday.
Last month, the ATO said it was not anticipating any further outages in the short term, after it prepared users for planned disruptions to its online systems in a bid to fix the problems lingering from last year.
A week prior, the ATO's business reporting system SBR1 experienced a "minor disruption", which resulted in the tax office taking its systems offline that weekend to conduct "critical system maintenance" as it sought to restore systems to full functionality.
The agency also undertook a significant amount of work over the Christmas break to ensure its website, portals, and hardware were functioning properly.
The storage hardware in question was upgraded in November 2015 by Hewlett-Packard Enterprise (HPE) and was seen by the ATO to be "state-of- the-art" at the time, with the ATO noting last year it was "basically the same" hardware used by other large clients of HPE.
The ATO's website, tax agent, and business portals initially crashed on December 12 as a result of a hardware issue. The outage continued through to December 13, when the ATO called in HPE to help it determine the underlying cause of the problem that the ATO said was encountered for the first time anywhere in the world.
Three days later, Commissioner of Taxation Chris Jordan announced an independent review into the "unprecedented failure" and called it the ATO's worst unplanned system outage in recent memory.
"This was an extremely unusual and unfortunate event," he said in a statement. "The issues we have experienced this week do not relate to our overall IT capability or skills."
At the same time, the ATO said almost everything was back up and running, but did admit that "some" data corruption was experienced as a result of the hardware-related incident, and noted it was in the process of having the data fully restored from a back-up.
On December 20 -- more than a week after the storage hardware failure caused the crash of its online services -- the ATO said it was still experiencing reduced functionality across some of its systems.
"What compounded the problem beyond the initial failure was the subsequent failure of our back-up arrangements to work as planned," Jordan explained previously. "The failure of our back-up arrangements meant that restoration and resumption of data and services has been very complex and time consuming."
Last week, the ATO announced it had appointed PwC to conduct an independent review into the hardware incident, with the tax office expecting the consultancy firm's review to provide insight into what actually happened and why, and what needs to be done to ensure the same incident does not occur in the future.
At the time, the ATO said it chose PwC to conduct the independent review due to the firm's "specific expertise" with the storage hardware at the centre of the incident.