An economist has raised concerns over NZ First's proposed reform for KiwiSaver contributions - and claimed they're not feasible.

NZ First recently promised to make it compulsory and increase contributions from employers and workers to 10 percent - offset by a tax cut.

Simplicity chief economist Shamubeel Eaqub says he approves of the idea of a compulsory scheme, but warns we can't afford a tax-funded one.

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