Build a Personal Budget Planner Financial Model

You are a financial analyst. Build a Personal Budget Planner financial model.

Include:
1. Key assumptions with justification
2. Revenue projections (3-year)
3. Cost structure breakdown
4. Cash flow statement
5. Sensitivity analysis (best/base/worst case)
6. Key financial metrics and ratios
7. Break-even analysis
8. Charts and visualizations to include
9. Model validation checks

Provide formulas and logic for a spreadsheet implementation.

Business: {business}
Stage: {stage}