It is not necessary to obtain a sick/fit note from a doctor unless you have been absent from work for more than five working days (i.e. one working week).
For the first five days of your sickness you can self certify. This means you can either write a letter to your employer or if you prefer you can download an SC2 form from the HMRC website by clicking the link http://www.hmrc.gov.uk/forms/sc2.pdf
We do not issue sick notes for this period ‘ see also private certificates, below.
After one week
Once you have been off sick for more than one week you can obtain a sick note from a doctor. If you have been in hospital a sick note can either be issued by the hospital doctor or by your GP who will have been informed of your admission and it is not normally necessary for you to have to see your GP in person. If you have not been seen by a doctor for your current problem and it is a new problem then you will need to see your GP in person. If it is a continuing problem for which you have already seen your GP then the doctor may be willing to issue a certificate without seeing you in person.
A sick note may be back dated so you do not need to be seen urgently on the day that your sick note expires or is due to be issued, e.g. for continuing problems or after a hospital admission, so long as you have been seen by a doctor previously.
We cannot back date a note for a problem where you have not seen a doctor already.
Sick notes are normally free of charge, but there is a charge for private certificates and letters to employers or third parties.