The company is developing software for different customers
The company wants to easily differentiate between works that can be billed to the customer, so they know how many hours should be invoiced/charged. These works can be meetings, research, development, bug fixing, etc.
The company also wants to track how many hours are logged as non-billable work. These cannot be cahrged/invoiced to a client. This can be crucial to identify problems, e.g. clients or teams where the non-billed hours are more than expected. The company can start to work on improvmenets or changes to reduce spending time on non-billable work and improve overall efficiency. These non-billable works can be pre-sales, creating proposals, invoicing, and processing payments, administrative tasks, etc.
The company is working with internal and customer projects
The company distinguishes between billable and non-billable working time on the basis of whether it was booked for a client project or an internal project.
The company wants to know at the end of the project, or at the end of the period how much to bill each customer.
It is the most suitable for this company to differentiate billable and non-billable work at the project level in Jira.
All work performed within a customer project is usually invoiced to the customer. But not all completed work will be billable in every client project, so billing should be set at the worklog level.
In the end the company want to see how much is the billable and the non-billable work in the customer projects.