This is always an interesting topic as the consulting leg of a business tends to want to bill hours every which way (including retainers). I've seen several implementations of this where, as Amy mentioned, you utilize the usage charge model which is billed in arrears; recurring charges are helpful if you have a managed services agreement you need to bill out monthly. On a similar note, we internally had a method of using Zuora to bill for consulting hours as follows: a. We used Harvestapp.com for time tracking. This was beneficial because of the ease of use of the application and their apps to help prevent revenue leakage. Some of the more cumbersome interfaces like NetSuite's employee center was too clunky and harder to adopt. b. We created an integration between Harvest and Zuora that would copy the approved hours to Zuora usage records each day automatically. We also had a manual push option in the event our billing department couldn't wait (e.g. month end close). c. Once all the usage records where in Zuora, we had two different invoice templates, one with usage and one without. This is a more elaborate example but demonstrates that the flexibility is there if you have the need for a more robust and scalable solution outside of csv file uploads.
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