Meridian Energy Ltd (Meridian) is a leading generator of renewable energy and retailer of electricity to customers in New Zealand and Australia. Meridian’s Asset Management (AM) is essential to realise value from its assets. This project report evaluates the planning accuracy of timing, duration and costs of non-annualised major projects within Meridian’s hydro AM. It aims to give recommendations for actions in the areas of improvement. Meridian’s AM is divided into the AM planning process and the project delivery. Specifically, in the Asset Management Plan (AMP), the CAPEX and time estimates for major projects are widely underestimated. There are various technical, psychological and political-economic root causes that create these inaccuracies. In the initial AM planning, for the project delivery and the feedback loop, mitigation techniques to tackle the underlying factors of inaccurate planning data in the AMP were found. The key benefits of improving AMP estimates are to encourage the present continuous improvement culture as a whole and to maintain the good relationships with the executive team.