@Perry, Christopher The rule can be created through the API. However, cost will not be allocated to the target with no usage. Unfortunately, there is no work around. We have an item in our backlog to allocate charges to targets even when they have no usage. For now, there is no definite timeliness for the feature availability.
Edit:
Cost must be present for each month for the allocation to work for that month.
Hope this answers your question!
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