The Finance Minister is preparing to tweak the Family Boost payment plan, admitting IRD had the wrong numbers on eligible families.

Data to April 9 reveals 249 families received the maximum payment of $975 dollars a quarter - since the scheme came into effect last year. 

Nicola Willis had said 21,000 families were eligible when launching the policy, but now concedes the modelling was wrong.

She says she wants to make sure families in need get the money.

"We put aside hundreds of millions of dollars for this policy because the uptake has been lower than the IRD basically estimated - we're not on track to actually get all that money out the door."

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