Use the reimbursable ledger in order to keep track of billable costs, that are not time related. This can be for example travelling costs, material etc. You can assingn the status "Billed" if you've already included a reimbursable cost in an invoice. If you are using Xpert-Timers billing system, the status will be assigned automatically.
This is an additional module and can be purchased in the order process of Xpert-Timer Pro and Enterprise.
Please refer to the manual for further details about the reimbursables module.
Here's a screenshot of the reimbursable ledger: