How do I see what's outstanding at a point in time?

Open Reports → Aged Debtors (for sales) or Aged Creditors (for purchases). Set the "as at" date to the point in time you want. The report shows each contact's outstanding — net of any payments and active bad-debt provisions — bucketed by aging (Current / 1–30 / 31–60 / 61–90 / 90+). Export as PDF or CSV for board packs or auditors. The as-at engine walks back through the GL, so the figure matches what you'd have seen if you'd run the report on that date live.