Delays in core aspects of the personally controlled electronic health record initiative could prevent consumers and practitioners from using the e-health records before September this year.
The $628.3 million project was expected to deliver e-health records from 1 July.
But Department of Health and Ageing deputy secretary Rosemary Huxtable told a Senate estimates hearing this week that consumers would only be able to register for a personal record in Medicare offices and via phone from that date.
An online registration portal, to be fed through ehealth.gov.au and the Federal Government's single sign-on portal at australia.gov.au, "may not be able from July 1" according to Huxtable.
"We are pushing very hard to have from 1 July but it may come some weeks after that," she told senators on Wednesday.
Once registered, consumers would be able to enter their own personal health notes, including allergies and adverse reactions to medicines.
However, general practitioners - seen as the core users of the e-health record initiative - would not gain access to functionality such as uploading existing records and new information before September, according to Huxtable.
"Then you reach a point where you get to see a record that's populated with shared health summaries, event summaries and the like and then over time there's additional functionality that's added around medication management, for example," Huxtable said.
"It is an evolutionary process."
Industry sources have attributed delays around aspects of the system relating to GP use to significant pressures on NEHTA's timeline to develop and ratify specifications for the system.
In January, NEHTA halted work in lead implementation sites to fix discrepancies in test system specifications, causing delays of up to six weeks in some sites.
Practitioners and clinics within the 12 lead implementation sites were expected to transition to the full production environment from 1 July but it is understood that key contracts governing that arrangement are yet to be finalised.
NEHTA staff involved in the project had foreshadowed potential delays to the online registration component of the record in recent speeches.
Key deadlines for other components of the system have also shifted several times in the past few weeks.
While a business-to-business gateway and template service for specifications is expected to be ready for service and testing this week, a consolidated view of healthcare data would not be available until mid-August.
In addition, the deadline for availability of data from Medicare repositories - initially slated for availability in mid-July according to mid-May documentation - is now "planned for the end of 2012", according to a presentation given to vendors this week.
Health minister Tanya Plibersek has asserted in several public speeches that the PCEHR was a "journey" that wasn't a "matter of 'flick a switch' and away you go".
NEHTA has called on GPs to more actively participate in the national initiative and adopt software compliant with the authority's specifications and standards.
It is expected that much of the clinical software used by GPs will be compatible, with a total of 23 vendors having agreed to integrate with the national record repository.
But continued concerns over lack of support for GPs and potential insecurity of the records has led the Royal Australian College of General Practitioners to warn against early adoption of the records.
"By design the PCEHR is opt in for both clinicians and consumers," it said last week.
"Both have the choice of involvement and its timing, based on their individual assessments of risk and benefit."
The department expects 500,000 Australians to take up the record by the end of the 2013 financial year, reaching up to 2.6 million in four years' time.