According to Patient.co in the United Kingdom, a Med 5 certificate states that a patient is fit or not fit for work. As of April 2010, the Med 5 certificate has been replaced by a Statement of Fitness for Work document.
To be reviewed for a Statement of Fitness for Work, previously a Med 5 certificate, the patient must be off work for more than 7 days. The patient can receive this document the day of his health assessment at a primary care provider. Otherwise it is available after his assessment or after submitting a report from another doctor or health care professional. This type of form is used to receive available sick pay or benefits when the patient is out of work.