This paper provides the background and overview of the development of Technical Specification (TS) 1170.5, released for public comment in February 2024 and published in 2025. The paper also serves as an introduction to the second of two special issues of the Bulletin of the New Zealand Society for Earthquake Engineering, including a total of eight papers providing supporting technical background for changes to NZS 1170.5:2004 and other considerations during the development of TS1170.5:2025.  This is the first major update to NZS 1170.5 since 2004. These special issues are expected to be of interest to practicing engineers and researchers wanting an in depth understanding of the basis for the changes found in TS 1170.5 and future standards development committees.   The paper concludes with a brief introduction to ongoing efforts under Stage 2 of the Seismic Risk Work Programme.