A careful balancing act on how far banks should have to go to prepare for a rainy day. 

Parliament's Finance Select Committee is currently seeking feedback on whether the Reserve Bank's capital requirements for banks should be changed. 

The current rules are stringent and costly. 

Massey University banking expert Claire Matthews told Mike Hosking we also can't go too far the other way. 

She says if a bank fails, and there isn't enough money to pay people out, that will have a huge impact on the whole economy. 

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