The bulletin intends to provide insights to Consultants in the preparation of their cost estimates to better inform their project estimates in which the NTA is the approving authority.
The bulletin is updated annually, or earlier if the macroeconomic conditions continue unstable.
The latest version of the bulletin was published in June 2026 , replacing the May 2025 bulletin and supplementary notes.
It should be used to provide guidance to Sponsoring Agencies on the treatment of future inflation from June 2026 onwards.
The bulletin and related material can be accessed at the 2026 NTA Inflation Bulletin – publication page