Less than 7 days
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 on the HMRC website.
Seven days or more
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). Following assessment by one of our GPs, a medical certificate, called a 'Statement of Fitness for Work’ (see below) may be issued for you to take as evidence of your illness to your employer.
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.
Statement of Fitness for Work - ’Fit Note'
The 'fit note' was introduced on 6 April 2010. With your employer's support, the note will help you return to work sooner by providing more information about the effects of your illness or injury.
For more information see the DirectGov website.