Precursor terrorism offences, which criminalise activity occurring at the pre-inchoate stage on the theory that this will prevent the subsequent commission of terrorist acts, have been a prominent feature of post-9/11 counterterrorism law. However, in late 2021, the New Zealand Parliament enacted the Counter-Terrorism Legislation Act 2021 (CTLA), a substantial reform which included several new precursor terrorism offences. The purpose of this article is to explain how this transpired, and to examine the precursor offences created by the CTLA. The article first situates the CTLA against the background of New Zealand's counterterrorism law after 11 September 2001 and before the Christchurch mosques attack of 15 March 2019. Secondly, it outlines the changes implemented by the CTLA — with the focus being on the new precursor terrorism offences, particularly the planning or preparation offence. Thirdly, based on the experience in comparative jurisdictions with similar precursor terrorism offences, it discusses the issues that are likely to arise with criminalising precursor conduct. While the drafters of the CTLA were clearly aware of these issues and mitigated some of them to a degree, others are likely the unavoidable consequence of creating precursor terrorism offences, especially a general offence of planning or preparation.