# Financial Engine v5

## plus vs without
- plus: courier collects COD + shipping fees from receiver.
- without: courier collects COD only; customer bears shipping fees in settlement/invoice.

## Core calculations
Shipping before tax = delivery fee + overweight fee + COD cash commission + visa commission + service cost.

Tax mode:
- include_pf: tax is recorded but not added on top.
- add_pf: tax is added to shipping charged.
- without_pf: tax is not charged.

## Safety rules
- No financial record should be deleted after approval.
- Use reversal cash movements instead.
- A shipment cannot appear in two active COD settlements.
- An approved invoice cannot be edited; use credit note or cancellation workflow.