How long have you been ill?
I’ve been ill 28 days or LESS
If you have been sick for 28 days or less, you will need to self–certify. www.gov.uk/taking-sick-leave.
You can complete it online.
I’ve been ill MORE than 28 days
If you have been sick for more than 28 days you might need a Sick note from the Doctor
If you are off work due to a hospital admission, the Sick note needs to be issued by the hospital. It will need to cover the period of time you were in the hospital and the expected recovery period, if applicable.
When do I need a Fit Note?
The NHS Information website provides further details about Sick or Fit Notes.