> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tesouro.com/llms.txt
> Use this file to discover all available pages before exploring further.

# External bank accounts

> What an external bank account is, why it exists, and how it fits into ACH money movement.

An external bank account is a pointer to a deposit account at a bank Tesouro doesn't hold the funds at. Tesouro never sees its balance, never moves money on it directly, and never holds funds in it. The only thing the pointer enables is ACH push and pull between that bank and an [internal bank account](/embedded-banking/guides/bank-accounts/internal-accounts).

External bank accounts are a top-level resource at `/embedded-banking/v1/external-bank-accounts` — they aren't nested under an internal bank account. They belong to the organization that connected them, and any internal bank account on that organization can use a `VERIFIED` external bank account as an ACH counterparty.

## Why they exist

Assuming the business customer has a bank account with some financial institution somewhere, it needs a way to move money between that existing bank and the deposit account Tesouro just opened for them. External bank accounts give the [ACH rail](/embedded-banking/guides/money-movement/ach) a verified, addressable target on the other end.

The verification is the load-bearing part. Tesouro doesn't take the user's word that they own the outside account — micro-ACH deposits prove control of it before any real money moves. Trusted callers (typically platforms sitting higher in the hierarchy) can self-attest verification instead of going through the deposits, but that's a scoped exception. See [Linking an external bank account](/embedded-banking/guides/bank-accounts/linking-external-accounts) for both paths.

## What's on the record

The response shape is deliberately thin. After connection you get:

| Field                | Notes                                                                                                                                                                          |
| :------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `id`                 | Identifier used in every later call against this external bank account.                                                                                                        |
| `accountNumber`      | Masked on every read after the create — Tesouro returns only the last four digits.                                                                                             |
| `routingNumber`      | Full routing number of the outside bank.                                                                                                                                       |
| `type`               | `CHECKING` or `SAVINGS`.                                                                                                                                                       |
| `nickname`           | Display label set at connect time.                                                                                                                                             |
| `nameOnAccount`      | Account holder name on file at the outside bank.                                                                                                                               |
| `verificationStatus` | `UNVERIFIED`, `VERIFICATION_SENT`, `VERIFIED`, or `FAILED` — see the [statuses table](/embedded-banking/guides/bank-accounts/linking-external-accounts#verification-statuses). |
| `accountStatus`      | `ACTIVE` while the external bank account is usable. Moves out of `ACTIVE` when the bank itself signals the underlying account is unreachable.                                  |

## What you can't do with them

* **No balance.** Tesouro has no read-access to the outside bank, so any "balance" you display has to come from elsewhere.
* **No non-ACH rails.** Internal-to-internal book transfers, RTP, and FedNow don't accept an external bank account as a counterparty — only ACH does.
* **No mutation of account or routing after connect.** You can update the `nickname`, but if the underlying account or routing number changes, connect a fresh external bank account.

## Where to next

* [Linking an external bank account](/embedded-banking/guides/bank-accounts/linking-external-accounts) — the three-call connect/link/validate flow and the verification statuses.
* [Troubleshooting](/embedded-banking/guides/bank-accounts/troubleshooting) — what to do when micro-deposits don't arrive or verification fails.
* [ACH transfers](/embedded-banking/guides/money-movement/ach) — how a verified external bank account is used as a transfer counterparty.