A MIC can operate in a few different ways. Some are operated by a manager outside the MIC, and some are operated by the MIC itself. Management fees can be made inside the MIC or charged to the MIC, or the income can just be left in the MIC, and employees paid by the MIC.
Either way, there's no tax leaving the system. An outside manager could pay corporate taxes, but it's solidly within the current legislation for a MIC to be its own manager as well.