I have attached a copy of the HSE guide to reporting of accidents for schools.
I get asked on courses how long should you keep hold of accident records. The HSE guide here says minimum 3 years. However remember a child casualty can claim for an injury up to 3 years after their 18th birthday. So technically it could be up to 21 years if the child gets an injury at 1 years old.
‘Special rules apply for children or patients being treated under the Mental Health Act 1983. The time limit (limitation period) does not begin for these people until the legal incapacity is removed. In the case of a child, the three year time limit would begin from the date of their 18th birthday and in the case of a patient treated under the Mental Health Act 1983, the three year deadline would begin from the date they were discharged as a patient.’