New Zealand Superannuation (NZS) Fund Contribution Rate Model

This is the New Zealand Treasury's spreadsheet-based model that is used to calculate the New Zealand government's capital contribution to the New Zealand Superannuation Fund (NZSF). The model was updated at the time of the release of the Half Year Economic and Fiscal Update 2024 (HYEFU 2024) in December 2024. This model calculates the contribution rate for pre-funding New Zealand Superannuation (NZS) under the legislated formula in Section 43 of the New Zealand Superannuation and Retirement Income Act 2001. From this contribution rate, which is expressed as a percentage of nominal GDP, the government's capital contributions to the Fund, and in later years withdrawals from the Fund to the Crown, are derived. The only exception to this is the contribution for the current fiscal year, 2024/25, which has not been changed from the value calculated at the Budget Economic and Fiscal Update 2024 (BEFU 2024). This is because the monthly payments to the NZSF in this year are based on equal instalments of this annual amount. Since the last release with the Budget Economic and Fiscal Update 2024 (BEFU 2024) the model’s data inputs have been updated. Specifically, the model uses the latest five-year forecasts provided by the NZSF of the Fund’s earnings and tax payments and those of NZS expenses made by the Ministry of Social Development, as well as Treasury’s longer-term projections of nominal GDP and aggregate net (after-tax) NZS expenditure.