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

# Billing Address Overview

Save a billing address for virtual card issuance on the caller's account. The address is saved as a `BILLING` user address and can later be passed to `createVirtualCard` as `userAddressId`.

When `authUserId` is provided, the address is saved for that authorized user's underlying user while remaining attached to the caller's account. The `authUserId` must be an ACTIVE non-owner authorized user assignment on the caller's account.

If an identical billing address already exists for the target cardholder on the caller's account, the existing address is returned instead of creating a duplicate. Matching is done on address fields, account, target user, and `BILLING` type.

<Info>
  **Prerequisites:** a Bearer token with the `CREATE_VIRTUALCARD` scope.
</Info>

<Note>
  **The billing address must be verifiable**

  This mutation stores the billing address. It must be a real, deliverable **US** address (`US`, `USA`, or `United States`) with a correct city, state, and ZIP, and **PO boxes are not accepted**. The USPS/Smarty check runs when a virtual card is created — an address that can't be verified there causes card creation to fail with `VC-0025`. See [Address Formatting Requirements](/concepts/address-formatting-requirements) for the full field rules and examples.
</Note>

## How it fits together

1. Save an address with `addVirtualCardAddress` — you get back a `userAddressId`.
2. Pass that `userAddressId` to [`createVirtualCard`](/features/create-card). It takes precedence over any inline `billingAddress`.
3. Reuse the same `userAddressId` across as many cards as you like — the address is stored once on the account.

You can also skip pre-saving entirely and pass a `billingAddress` object inline on `createVirtualCard`; a matching saved address will be reused, or a new one created.

## Next steps

<CardGroup cols={2}>
  <Card title="Add virtual card address" icon="map-pin" href="/features/add-billing-address">
    The full mutation contract — parameters, responses, examples, and error codes.
  </Card>

  <Card title="Create a virtual card" icon="credit-card" href="/features/create-card">
    Put the saved `userAddressId` to work issuing a card.
  </Card>
</CardGroup>