Is there a way to forecast my next month's Azure costs under a CSP Azure Plan?

Yes — Azure Cost Management includes forecasting tools that project upcoming costs based on recent usage trends, available within your own tenant regardless of billing model. For more predictable workloads, this forecast tends to be fairly reliable; for highly variable usage, it's more of a directional estimate.

A CSP partner can also help build a more tailored forecast if you're planning for a specific change (like scaling up a workload or adding a new project), factoring in things the automated forecast might not fully capture.