This technical report is designed to accompany the 2023 edition of the Homelessness Monitor England and particularly the analyses presented in Chapter 5, which focuses on core homelessness and the forward projections which examine the potential impacts of a wide variety of policy options and scenarios. It follows similar lines to a very detailed technical report which accompanied the 2020 edition of the Homelessness Monitor England (published in early 2021). The current round of the Monitor has involved a more extensive update of the core homeless estimates and the projections modelling, partly thanks to a lot of new data (e.g. 2021 Census) and having more data covering the first four years of the post-Homelessness Reduction Act (HRA) regime and its associated data system ‘H-CLIC’. In addition, work had been progressing on updating and refreshing the underlying sub-regional model of the housing market in England.