Three Way Matching

Matching Logic

• PO ↔ Invoice: Match by PO number in invoice description/reference
• Invoice ↔ Payment: Match by invoice number in payment reference
• Tolerance: R0.05 or 0.1% configurable (see backend/core/matching/tolerance.py)
• Date window: Payments within 30 days of invoice date

Key Files

• backend/core/matching/three_way_engine.py — main engine
• backend/core/matching/models.py — Invoice, Payment, POLine dataclasses
• backend/core/matching/strategies/ — matching strategies
• backend/core/matching/reporter.py — discrepancy reporting
• backend/core/matching/audit.py — audit trail

Discrepancy Types

• Amount mismatch: Invoice total ≠ payment amount (outside tolerance)
• Missing PO: Invoice has no matching PO in Sage
• Partial payment: Payment amount < invoice amount
• Overpayment: Payment amount > invoice amount
• Unmatched: No cross-reference found

Output

Present matching results as a table with columns: Supplier, Invoice#, PO#, Amount, Payment, Status (matched/unmatched/discrepancy).