Under Self-Service portal settings, when you have the option "Show in work log differential hours based on SLA configuration" set to "Yes", the application will look for the SLA configuration and show the operational hours accordingly while adding a worklog.
This will allow you to add charges and the same will be added while generating a bill.
When there is no contract associated with the request, to include “Non-Operational hours”, you need to enable the option “Include non-operational hours”.
The SSP relevant option for the same is “Include non-operational hours to time spent, while adding a new worklog”.
If the option is set to “Yes”, then the non-operational hours check will be automatically enabled while adding a worklog.
If it is set to “No”, we need to manually enable the check box to include Non-Operational hours to your worklog.