Paid Parental Leave is administered by the IRD, and is available for 26 weeks after you go on parental leave. You can apply through MyIR. You will need a letter form your midwife confirming your due date or the date of your baby’s birth.
To be eligible, you need to have worked at least 10 hours per week on average for 26 of the last 52 weeks. This does not all have to be for the same employer. This page from the IRD has more clarification on work requirements. This tool from the IRD will help you find out if you are eligible for Paid Parental Leave.
Paid Parental Leave will pay you your usual salary, up to a maximum level. The maximum payments change each year and can be found on the IRD website here, along with how payments are calculated if you are an employee.
If you are self-employed, you are usually still eligible for paid parental leave. This page from the IRD has information for self-employed people on how payments are calculated.
You cannot have Best Start payments and Paid Parental Leave running at the same time. Any Best Start payments you receive must begin after your Paid Parental Leave ends.