IRD has posted Final V1.0 of the Payroll Specification for the 2017-18 period on their website.
This document is written for payroll developers but it is full of examples and all payroll practitioners should be referring to this document to ensure their payroll system is compliant based on IRD stated requirements.
Use the following link to get your copy: http://www.ird.govt.nz/software-developers/technical/ir-file/ir-file-payroll-specifications.html.
NZPPA supporting payroll since 2007!