Sickness Certificates
If employees are off work for 28 days or less, they do not need to give their employer a fit note or other proof of sickness from a medical professional.
If the period of sickness started before 10 December 2021, employees do not have to provide a fit note if they are off work for 7 days or less.
When they return to work, their employer can ask them to confirm they’ve been off sick. This is called ‘self-certification’. The employer and employee will agree on how the employee should do this. They might need to fill in a form or send details of their sick leave by email. Please use the links below for more information.
https://www.gov.uk/taking-sick-leave?s=09
HMRC website.
Evidence that you are sick
If you are sick for more than 28 days (if sickness started after 10th December 2021), your employer can ask you to give them some form of medical evidence to support payment of SSP (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'
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 (where this information was sourced)