Retrieve the current status of a previously-created tax registration order.

Important: GET returns a status summary, not the full submitted order. The response includes id, orderGuid, orderPhase, orderStatus, accountNumbers, taxRates, and agencyAccounts only. Submitted business details, state info, account info, and responsible parties are not returned. Retain a local copy of the submission if you need to re-display it.

Not-found semantics: when {orderGuid} does not match any existing order, the API currently returns HTTP 400 (rather than 404) with body {"statusCode": 200, "message": "success", "data": {"partnerOrder": null}}. The body's statusCode and message fields are misleading in this case — they say success even though the underlying record was not found. Detect not-found defensively by checking data.partnerOrder === null rather than trusting the status fields.