It is the end hirers responsibility to determine a contractor’s IR35 status and provide them with an SDS. This applies to both Public and Private Sectors.
Currently, the law states that it is only up to the public sector end hirer to assess their contractors for IR35 and determine their status.
Historically, private sector organisations could leave it to the individual contractor. However, these rules have now changed. So from April 2021 even if you are a contractor and used to self-assess your own IR35 status, you no longer have this responsibility. The legal responsibility for assessing IR35 – public or private – falls with your end hirer.