Design, Sources and Methods

Collaborative Development

The publication design was shaped through:

• a Discovery Stage in October 2023, involving direct engagement with federal and state agencies, market analysts, academics, and CPI experts to identify priority needs
• a Public Consultation process (16 November – 15 December 2023), where formal submissions were invited on the proposed design, including timing, content, and methods
• ongoing engagement with key users throughout the development process, ensuring emerging needs and perspectives were considered. 

Key Themes from Feedback

The primary requests voiced by stakeholders included to:

• prioritise accuracy and data coverage, over improved timeliness of the publication’s release after the end of the reference period
• maintain the same level of detailed commentary and analysis as published in the quarterly CPI
• publish monthly data content consistent with the current quarterly CPI data series
• continue some quarterly data series for timeseries analysis and legislated indexation requirements.

Find out more about the publication format and data tables that will be available with the complete Monthly CPI.  

The move to a complete Monthly CPI represents a significant improvement from the legacy mix of monthly, quarterly, and annual price collection. Under the current approach:

• 50% is updated monthly.
• 41% is updated quarterly.
• 9% is updated annually.

This approach, shaped by historical system and data constraints, limits the quarterly CPI’s responsiveness to emerging inflationary trends. This collection approach impacts the current Monthly Consumer Price Index Indicator, which reflects up-to-date prices for around two thirds of goods and services in any given month. 

To address this the ABS has:

• increased collection frequency from quarterly to monthly for the majority of items
• integrated new data sources, including administrative data and transaction records
• invested in new cloud-based systems.

These changes will enable a more responsive and precise measure of inflation across the full CPI basket.

Increased frequency of collection

From April 2024, the ABS increased the frequency of direct business data collection, transitioning many items from quarterly to monthly reporting. To reduce the reporting burden, we are also leveraging: 

• automated online price web scraping
• government sourced administrative datasets.

Figure 1 shows with increased collection and data, most of the items in CPI basket will be priced every month. A small number of prices will continue to be collected annually or quarterly in line with when price changes typically happen for those items.  

Annual collection will continue for health insurance, education fees and property rates. Prices will continue to be collected quarterly for Other financial services (items such as stamp duty, real estate services and accounting services), as these prices do not tend to change frequently. This is in line with international best practice as price collection frequency should align with the likely frequency of change.

Note: 87% of the CPI by weight will be collected monthly in the complete Monthly CPI. Annual collection will continue for 9% of the CPI, including health insurance, education fees and property rates. Quarterly collection will continue for 4% in Other financial services (items such as stamp duty, real estate services and accounting services), as these prices do not tend to change frequently.

Commencement of monthly data collection 

The CPI is made up of 87 Expenditure Classes (ECs), each representing a group of related goods and services commonly purchased by households. These ECs form the foundation of the CPI and capture price movements for specific set of items within the CPI basket. Table 2 shows the commencement dates for monthly data series for each EC, reflecting the staged roll-out of increased collection frequency from April 2024. 

Use of administrative data to enhance coverage and compile monthly prices 

• Child Care administrative data - Measurement of Child care costs will shift from sample-based collection of fees data and modelled estimates of subsidies to direct measurement using a census of actual fees paid and subsidies received. This data will be provided to the ABS by the Services Australia with a lag of one month due to the time needed to process the data.
• Insurance web scraped market prices – House, contents and motor vehicle insurance prices will be collected using web scraping from major insurers. This new data source enables monthly rather than quarterly measurement and is more representative of the market, better quality, and more reliable.
• Medical and Pharmaceutical Services - Data from the Pharmaceutical Benefits Scheme (PBS) and Medicare Benefits Schedule (MBS) are now received monthly, enhancing insight into medical service and medicine costs.
• New Dwelling Prices - A new method has been developed to enable Attached Dwellings price changes to be modelled monthly, from April 2024 using the existing cost data. This, along with increasing the frequency of collection for Installed appliances prices, brings the New dwelling purchase by owner occupiers Expenditure Class (EC) to full monthly coverage.

The release of the complete monthly CPI is underpinned by significant system and infrastructure upgrades delivered through the ABS’s Big Data, Timely Insights: Phase 2 (BDTI2) program. As part of the ABS’s 10-year modernisation vision, BDTI2 has built on foundational cloud capabilities developed in Phase 1 and is enabling the production of more timely, accurate and reliable statistics for decision-makers and data users.  

For the complete Monthly CPI, BDTI2 delivers modern statistical platforms that increase automation, reduce risks associated with outdated systems, and ensure secure handling of sensitive business and market data. Modern and flexible processing and analytical tools – including new visualisation functionality – will reduce manual processing, support faster integration of high-frequency data, and improve the efficiency and consistency of economic statistics production.

The current Monthly Consumer Price Index Indicator (“the Indicator”) was introduced to provide more timely insights into consumer price changes. However, the Indicator has some limitations as it relies on existing price collections that were not designed for monthly inflation reporting. For example, when prices are not collected in a given month, earlier prices are ‘carried forward’ to produce a monthly estimate in the subsequent month. The final release of the Indicator is scheduled for publication on 29 October 2025 for the September 2025 reference period. For more information on how the Monthly Indicator is compiled, see Introducing a Monthly Consumer Price Index (CPI) Indicator for Australia.

The complete Monthly CPI, with expanded monthly data collection, will provide comprehensive inflation information that was not possible with the Indicator. This shift to a complete monthly measure of the CPI will mean headline inflation will be reported as the annual movement in the monthly CPI. Previously, headline inflation was based on the annual movement in the quarterly CPI. The diagram below highlights the difference in calculating the annual movement of the Monthly CPI compared to the annual movement of the quarterly CPI.

The introduction of a complete Monthly CPI brings Australia’s inflation measurement in line with international standards. This development further aligns Australia’s approach with those of other leading economies, including members of the OECD and G20 (Group of Twenty). 

The ABS began publishing a monthly CPI indicator in October 2022. The indicator reflects up-to-date prices for around two thirds of goods and services in any given month, limiting its completeness.

The transition to a complete Monthly CPI, will provide more timely, comprehensive, and internationally comparable inflation data. This improvement will provide better information for monetary and fiscal policy decisions that have a direct impact on all Australians and reinforce Australia’s commitment to statistical best practice.