Period of sickness – 1-3 days - you do not need a certificate. For periods of 4-6 days sickness - your employer may require you to complete a self-certificate form SC2 which is available from your employer or the D.S.S.
For illness longer than 6 days - you will need to see the Doctor for him to issue a sickness certificate and for any subsequent renewal of the certificate. The only exceptions to this may be after hospital inpatient or outpatient attendance or for long-term sickness. The law states that you do not need to obtain a certificate from your Doctor for illness between 1-6 days. If your employer insists that you obtain one, this service is not covered by the NHS and a charge will be payable.