In an Hourly billing model, the billing is based on the number of hours spent. When you opt for this model, the ‘billable’ option for expenses and time entries in the project is checked, by default. The applicable billing rate depends on the company level setting and can either be User based or Time code based.
When the time or expense is approved, billable amount is automatically updated for a task. Billable amounts of individual tasks are rolled up to the summary task and eventually to the project level.
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