The organization sets up, runs and maintains a programme of internal audits that defines how often audits happen, the methods used, who is responsible, how audits are planned and how they are reported; in doing so it considers how environmentally important the processes are, any changes affecting the organization, and what earlier audits found. It sets the criteria and scope of each audit, chooses auditors and runs audits in a way that keeps them objective and impartial, and makes sure the relevant managers receive the results. Documented information is kept to evidence that the programme was carried out and what the audits found.
This control maps to 44 controls across 26 other frameworks. If you already hold one of them, the evidence you collected for it is the starting point here rather than new work.