# Loan Calculation Fix Summary

## Issue Identified
LOAN-000113 and 25 other loans had incorrect interest and processing fee calculations.

### Root Cause
**LOAN-000113 (Mwamba - 90 days):**
- Interest was calculated for **1 month instead of 3 months**: 5,000 instead of 15,000
- Processing fee used **old model rate (2%) instead of system settings (5%)**: 1,000 instead of 2,500
- Total was 56,000 instead of 67,500

**Other Loans:**
- **Boost loans**: Processing fee was using 12% instead of 2% (system settings)
- **Boost Plus loans**: Processing fee calculations were inconsistent
- **Imara loans**: Interest calculations were using wrong rates or durations

## Fix Applied
✅ **26 loans fixed** using `production_fix_all_loan_calculations.py`

### LOAN-000113 Corrections:
- **Interest**: 5,000.00 → 15,000.00 (+10,000.00)
- **Processing Fee**: 1,000.00 → 2,500.00 (+1,500.00)
- **Total**: 56,000.00 → 67,500.00 (+11,500.00)

### Verification:
✅ All values now correct:
- Principal: 50,000.00
- Interest: 15,000.00 (10% × 3 months)
- Processing Fee: 2,500.00 (5%)
- Total: 67,500.00

## Impact
- **26 active loans** had their calculations corrected
- Borrowers now see accurate loan amounts
- Outstanding balances are now correct
- All loan applications also updated to match

## Files Created
1. `production_investigate_loan_calculation.py` - Investigation script
2. `production_fix_loan_113.py` - Fix for specific loan
3. `production_fix_all_loan_calculations.py` - Comprehensive fix for all loans
4. `production_verify_loan_113_fix.py` - Verification script

## Next Steps
The loan calculations are now correct. The issue was in the loan creation/approval process where:
1. Interest was not being calculated for the full duration
2. Processing fees were using inconsistent rates

To prevent this in the future, ensure that:
- The `LoanApplication.save()` method correctly calculates interest for the full duration
- The `LoanProduct.calculate_interest()` and `calculate_processing_fee()` methods are always used
- System settings are properly synchronized with loan product models
