Have a think about everything your income pays for. The house, the food, the power bill, the kids' sport. Now picture it stopping for six months because you got sick.
That's what income protection is for. It pays you a monthly amount if you can't work because of illness or injury. And unlike ACC, it covers illness too, which is where most long-term claims actually come from.
You choose a wait period and a benefit period to balance the cost against the cover. For most working Kiwis, it's one of the most useful things you can have in place.