Are you talking about the parental tax credit  that you would be getting instead of paid parental leave?

If you are getting that then you would have to get the forms from them and apply for it seperately. Once you have #2 you call them and give them the DOB, they will then adjust the payments for having 2 children and then pay it when your next payment is due (depending on when you call) You then have 8 weeks to get the IRD # application for #2 into them (you need to wait for the birth cert) and then your payments will continue like normal. You can go online to their calculators and work out how much you would eligible to get once #2 is here (I think it is an extra $72 a week).

What I did was after I have Josh and was settled back at home I rang them up to give them the date of birth of the 2nd child. They will only pay you from the DOB. They told us we have 8 weeks to get them IRD # form back to them or the payments will stop. We received a cert of entitlement the other day and it had the amount that we will receive with the IRD # and the amount without the IRD #. We are now just waiting of DBM to send us Josh's birth cert to send a copy to IRD.

And good luck getting through to them at the moment, I have been trying ofr ages as they haven't put on the in work payment thing on our cert of entitlement and that $60 comes in handy every week.