A supplier invoice audit becomes more reliable when freight and accessorial fees are validated against charge-specific commercial rules.

A supplier invoice audit is stronger when service invoices connect to work orders, labor evidence, materials, and approved billing rules.

A supplier invoice audit can miss pricing and credit patterns when aliases, branches, and duplicate vendor records are treated as unrelated suppliers.

A supplier invoice audit needs an alternative evidence path for non-PO invoices instead of treating them as either automatic exceptions or automatic approvals.

A supplier invoice audit can miss real cost leakage when the visible price is correct but negotiated discounts, rebates, or allowances are absent.