## TL;DR

Dates like 04/05/2026 are ambiguous between US and international formats, and picking wrong shifts payment timing and period posting. Resolve with vendor country (US vendors use MM/DD, most others DD/MM), then sanity-check against the invoice receipt date and due-date terms. Store dates in ISO format internally and never guess silently: flag true ambiguities.

## Error

```text
Extracted invoice date: 04/05/2026 (ambiguous: April 5 or May 4)
```

## Steps

1. Check the vendor's country in the vendor master.
   Expected: US implies MM/DD/YYYY; most other countries imply DD/MM/YYYY.
2. Cross-check with related dates: due date should equal invoice date plus terms.
   Expected: The terms arithmetic disambiguates most cases.
3. Verify the date is not in the future and falls within a plausible window.
   Expected: Obvious misreads get caught.
4. Store the resolved date as ISO YYYY-MM-DD with the interpretation recorded.
   Expected: An auditable, unambiguous record.
5. If still ambiguous, flag for review rather than guessing.
   Expected: A wrong date misstates the period.

## When to use

- Extracted date has day <= 12 and could be either format
- International vendor base with mixed formats
- Payment terms depend on the invoice date

## When not to use

- Date is completely missing from the invoice
- Mapping dates to fiscal periods
- Timezone handling

## Compatibility

Extractor-agnostic. Vendor master country data required.

## Variant phrasings

### invoice date format ambiguous

### 04/05/2026 month day confusion

### US vs EU date on invoice

## Root cause

The US uses month-first while most of the world uses day-first, and invoices rarely label the format. OCR reads the digits correctly; the meaning is what is ambiguous.

## Edge cases

- Vendors operating in both formats need per-vendor configuration, not country default
- Some invoices print both order date and invoice date; label them before resolving
- Year boundaries (12/01 vs 01/12) affect period close; escalate these

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_gUbskVXYQfi5dqd1AzFC2Q