You do not require a doctor’s sickness certificate for any illness lasting seven days or less. Your employer may however require you to complete a self-certification form (SC2) which is available from your employer or please use link Self certification
Evidence that you are sick
If you are sick for more than seven days, your employer can ask you to give them some form of medical evidence to support payment of SSP (statutory sick pay). Information on statutory sick pay
It is up to your employer to decide whether you are incapable of work. A medical certificate, now called a ‘Statement of Fitness for Work’ (see below) from your doctor is strong evidence that you are sick and would normally be accepted, unless there is evidence to prove otherwise.
You could also provide evidence from someone who is not a medical practitioner, e.g. a dentist. Your employer will decide whether or not this evidence is acceptable. If your employer has any doubts, they may still ask for a medical certificate from your GP.
Statement of Fitness for Work – ’Fit Note’
Healthcare professionals issue fit notes to people to provide evidence of the advice they have given about their fitness for work. They record details of the functional effects of their patient’s condition so the patient and their employer can consider ways to help them return to work. Information on fit notes