Analyze the following hypothetical monolithic function (which calculates payroll taxes but handles UI logging, database connections, and email notifications) and refactor it. Break the code down into distinct classes or modules adhering strictly to SOLID principles. Specifically, identify the Single Responsibility Principle violations and separate concerns. Provide the refactored pseudocode and a brief explanation of how Dependency Injection is applied to decouple the high-level policy from low-level details.