From Health and Safety Executive:
Make sure you submit a RIDDOR report for a workplace accident where necessary…
RIDDOR puts duties on employers, the self-employed and people in control of work premises to report certain serious workplace accidents, occupational diseases and specified dangerous occurrences.
Our publication Reporting accidents and incidents at work explains what is required from employers and provides information about RIDDOR. HSE’s Accident Book can be used to record details of all work-related accidents including injuries that employers must report under RIDDOR.