If an employee works part of the day before going home sick, should this day count as sickness absence?

For statutory sick pay purposes, once an employee has begun work on a day, that day cannot count as a day of incapacity. However, if the employee arrives for work and does no work before going off sick, it is deemed to be a day of incapacity.

For the purposes of contractual sick pay and attendance management, it is for the employer to set its own rules as to how to count a partial day of sickness absence. It should set this out in its sickness absence policy.