Investment Decision Assurance is about providing independent assurance to ministers on high-risk central government investment decisions while helping Senior Responsible Owners (SROs) identify and address delivery risks as projects develop.
Why investment assurance matters
New Zealand spends a significant share of GDP on infrastructure, but we have not always achieved good value from this investment.
Decision-makers have often been asked to approve individual investments without clear, consolidated information about whether a project is strategically aligned, affordable or deliverable. This can make it harder to identify and address problems early, before they become more difficult and costly to resolve.
The National Infrastructure Plan identified a number of these issues. Of its 16 recommendations for long-term system improvement, three focused on improving how New Zealand identifies and prioritises the right infrastructure investments.
Strengthening the investment assurance system
In April 2026, as part of the Government response to the National Infrastructure Plan, Cabinet agreed to strengthen investment assurance. The changes are intended to improve the information available to ministers and ensure high-risk investments receive appropriate scrutiny to support good investment decisions.
Cabinet agreed to reconfigure the New Zealand Gateway assurance review model to better focus on the needs of ministers and Cabinet. It also agreed to transfer responsibility for coordinating external assurance activities for infrastructure investments from the Treasury to the New Zealand Infrastructure Commission.
This enables the Commission’s infrastructure expertise to be more directly applied to the independent assurance and advice ministers and Cabinet receive when considering infrastructure investments.
The Treasury continues to coordinate external assurance activities for non-infrastructure investments.
A single assurance process
Investment Decision Assurance brings together the Gateway review process and Infrastructure Priorities Programme (IPP) into a single, investor-focused system for infrastructure investments.
Gateway reviews
The Treasury Gateway review process provided independent expert reviews at key decision points. Through stakeholder interviews and document review, it provided a rapid assessment of the likelihood of successful delivery.
However, its primary focus was on supporting SROs. This meant that ministers and other investment decision-makers did not fully benefit from the independent advice generated through the process.
Infrastructure Priorities Programme (IPP)
The IPP was designed and managed by Te Waihanga to give current and future decision-makers greater confidence in infrastructure investments through a strong focus on strategic alignment, value for money and deliverability, based on a detailed review of the business case.
However, because participation in the IPP was optional and not embedded within government investment decision-making processes, ministers did not receive consistent independent investment advice across all projects.
Investment Decision Assurance
The new Investment Decision Assurance process combines the strengths of both approaches: Gateway’s SRO focus and interactive approach with the IPP’s investor focus and business case rigour.
The result is a single process that supports both ministers and SROs, while reducing the duplication and complexity of operating two separate assurance systems.
Investment Decision Assurance provides progressive assessment of a project’s priority, value for money and deliverability through the investment lifecycle. It provides assurance from the project initiation phase through to readiness for service and post project completion. This means ministers receive independent advice on whether a project warrants investment and whether it is likely to be successfully delivered.
Connecting to New Zealand’s broader Investment Management System
The Investment Decision Assurance review process, and the Commission’s role in providing assurance reviews, is part of the broader Investment Management System (IMS) owned and managed by the Treasury. The primary points of interface with this system include:
A Risk Profile Assessment is used early in investment planning to identify the inherent risk of a proposed investment. The resulting risk rating helps determine the assurance pathway and relevant assurance unit for that investment.
Agencies complete a Risk Profile Assessment for submission to the Treasury’s Investment Management System team. Where an investment is assessed as high risk, IDA reviews are mandatory and must be initiated by agencies at fixed points throughout business case development, project delivery and operation.
The Treasury provides a standardised Fitness Assessment for investment proposals submitted to Cabinet.
The assessment brings together the outcome of the relevant Investment Decision Assurance review with Treasury analysis of the agency’s past investment performance and the wider fiscal context. This information supports Cabinet decision-making and informs the Treasury’s overall recommendation.
The Infrastructure Investment Ministers Group reviews high-profile and high-risk investment proposals, as well as agency long-term investment plans, before Cabinet committee consideration. It also monitors relevant investments through delivery.
The Commission supports the group by providing findings from Investment Decision Assurance reviews and infrastructure expertise and advice where required.
Cabinet has separately established an assurance function for capital-intensive central government agencies covering asset management and long-term investment planning.
The Treasury is responsible for the policy settings for this function, while the Commission is responsible for coordinating infrastructure assurance.
This function is being developed in parallel with Investment Decision Assurance and is expected to launch in July 2027. It sits outside the scope of Investment Decision Assurance.
There are a range of other assurance and review products available to ministers and agencies. These include agency-initiated peer reviews and Independent Quality Assurance (IQA), minister-directed Project Reviews undertaken through the Commission’s statutory functions, and performance audits and inquiries undertaken by the Office of the Auditor-General.
Design of the new process
The new IDA process was informed by a breadth of research and experience, including interviews with users of both Gateway and the IPP, a review of the features, consistency, depth and strengths of both Gateway and IPP reviews, the Treasury and the Commission’s own experiences running the two systems and lessons learnt from overseas infrastructure assurance processes.
Agency representatives and key industry stakeholders also provided feedback through engagement sessions held jointly with the Treasury. All the insights and findings have made a critical contribution to the development of the Investment Decision Assurance and to ensuring that all decision-makers as well as SROs will find value in the new process.
Further information
Additional resources and background information.