It is not necessary to have a Doctor’s certificate until you have been absent continuously from work for seven days including weekends. After three days you must obtain a self-certificate (SC2) from your employer. If your employer insists on a private certificate for an illness of less than seven days duration then the Doctor will charge a fee of £10. If your illness continues for more than seven days then under the NHS your GP can issue an official statement (Med3) “fit to work certificate” to confirm your illness.