The Public Service Association has warned that National's KiwiSaver policy would impose a multibillion-dollar unfunded burden on public services including schools and hospitals.
National announced at its June 2026 conference it would make KiwiSaver compulsory from July 2028 if re-elected. The policy would gradually lift both worker and employer contributions to 6% each by 2032.
PSA national secretary Fleur Fitzsimons said National's costings accounted only for enrolling workers not yet in the scheme, ignoring the expense of lifting employer contributions for existing members. The union calculated a $4.5 billion shortfall over the five years from 2028 to 2033, using Treasury wage forecasts and a flat headcount assumption.
"It is irresponsible and a dereliction of duty not to properly fund election promises," Fitzsimons said. "This isn't chicken feed. There's no $4.5 billion money pot just sitting around."
Fitzsimons said agencies would absorb the costs through cuts and job losses.
National's finance spokesperson Nicola Willis said departments would need to plan for the higher contributions and that increased employer superannuation tax revenue would partly offset the expense.
"The additional cost will be able to be met from within future budgets so long as the government continues to carefully prioritise public money," Willis said. "I'm surprised the PSA doesn't see providing its members with greater financial security in retirement as a priority. National does."
When the government announced earlier KiwiSaver changes at the 2025 Budget, Treasury forecast employers would recoup around 80% of the cost by keeping wage growth below what it would otherwise have been.