List a regime's existing customers

Lists the customers the legal entity has already charged tax under a registration's regime, in the mode of the request, all brands combined, with their open liability. When a regime is blocked for new consumers (blocked_b2c), these existing customers keep their renewals, top-ups and refunds, and their tax is still charged and owed (spec §10.7).

For each customer: pendingRegistration, the tax charged before the entity registered (tax_pending_registration in the ledger, net of refunds): the open liability; chargedAsRegistered, the tax charged while registered; the regime's jurisdictions and the first and last sale. email and name are shown only if you can read that brand's customers.

summary has the regime's open liability per jurisdiction (the ledger balances), the number of customers, and pending amounts linked to no customer (unattributed). Customers are listed newest first; paginate with limit (1–100, default 25) and starting_after.

At a glance

REST: GET /api/v1/registrations/{id}/affected_customers
MCP tool: registrations_affected_customers
Operation ID: registrations.affected_customers
Scope: Legal entity
Permission: registrations:read
Risk tier: read
Dry run: Not supported
Idempotency: Not needed (read only)
Modes: Test and live
Pagination: limit (at most 100) and starting_after
Authentication: API key with the registrations:read scope
Since: M7

Request

Path parameters

Field	Type	Description
`id`	string	The registration (`regn_…`) or its regime's ID, e.g. `EU_OSS_UNION` or `US_SALES_TAX:TX`.

Query parameters

Field	Type	Required	Description
`limit`	integer (1 to 100)	No	Page size, 1 to 100 (default 25).
`starting_after`	`cus_…` ID	No	The `next_cursor` of the previous page.

Response

200 OK with a JSON object, a page of the list (newest first):

Field	Type	Description
`object`	`"list"`
`data`	array of object
`data[].object`	`"affected_customer"`
`data[].customerId`	`cus_…` ID
`data[].brandId`	`brd_…` ID or null
`data[].email`	string or null
`data[].name`	string or null
`data[].deleted`	boolean
`data[].jurisdictionIds`	array of string
`data[].pendingRegistration`	array of money
`data[].chargedAsRegistered`	array of money
`data[].firstSaleAt`	date-time
`data[].lastSaleAt`	date-time
`data[].transactionCount`	integer (at least 0)
`has_more`	boolean
`next_cursor`	`cus_…` ID or null
`registrationId`	`regn_…` ID
`regimeId`	string
`summary`	object
`summary.customerCount`	integer (at least 0)
`summary.customersWithOpenLiability`	integer (at least 0)
`summary.openLiability`	array of object
`summary.openLiability[].jurisdictionId`	string
`summary.openLiability[].pendingRegistration`	money
`summary.openLiabilityTotal`	array of money
`summary.unattributed`	array of money

Examples

Two consumers of a blocked OSS registration

HTTP

GET /api/v1/registrations/EU_OSS_NON_UNION/affected_customers
Authorization: Bearer or_test_…

Response (200):

JSON

{
  "object": "list",
  "data": [
    {
      "object": "affected_customer",
      "customerId": "cus_01m4tx5nj8emwbyf7y9vcf47xs",
      "brandId": "brd_01m4tx5nj8emwbyf7y9vcf47x4",
      "email": "lena@example.de",
      "name": "Lena Schmidt",
      "deleted": false,
      "jurisdictionIds": ["DE"],
      "pendingRegistration": [
        {
          "amount": "3800000",
          "currency": "EUR"
        }
      ],
      "chargedAsRegistered": [],
      "firstSaleAt": "2026-10-14T09:30:00.000Z",
      "lastSaleAt": "2026-10-14T09:30:00.000Z",
      "transactionCount": 1
    },
    {
      "object": "affected_customer",
      "customerId": "cus_01m4tx5nj8emwbyf7y9vcf47xr",
      "brandId": "brd_01m4tx5nj8emwbyf7y9vcf47x4",
      "email": "marie@example.fr",
      "name": null,
      "deleted": false,
      "jurisdictionIds": ["FR"],
      "pendingRegistration": [
        {
          "amount": "7980000",
          "currency": "EUR"
        }
      ],
      "chargedAsRegistered": [],
      "firstSaleAt": "2026-10-15T10:02:11.000Z",
      "lastSaleAt": "2026-11-15T10:02:13.000Z",
      "transactionCount": 2
    }
  ],
  "has_more": false,
  "next_cursor": null,
  "registrationId": "regn_01m4tx5nj8emwbyf7y9vcf47xk",
  "regimeId": "EU_OSS_NON_UNION",
  "summary": {
    "customerCount": 2,
    "customersWithOpenLiability": 2,
    "openLiability": [
      {
        "jurisdictionId": "DE",
        "pendingRegistration": {
          "amount": "3800000",
          "currency": "EUR"
        }
      },
      {
        "jurisdictionId": "FR",
        "pendingRegistration": {
          "amount": "7980000",
          "currency": "EUR"
        }
      }
    ],
    "openLiabilityTotal": [
      {
        "amount": "11780000",
        "currency": "EUR"
      }
    ],
    "unattributed": []
  }
}

Errors

Code	HTTP status	When	What to do
`validation_failed`	400	`id`, `limit` or `starting_after` is malformed.	Fix the fields listed in `details.issues` and send the request again.
`resource_not_found`	404	This entity has no such registration in this mode.	Check the ID and that your credentials are scoped to the right organization, entity, brand and mode.
`scope_required`	400	The request names no legal entity (an org key without `Ownrecord-Entity`).	Call the operation with credentials or a target at its level: an organization, a legal entity, a brand or the platform (`details.required_scope`).
`permission_denied`	403	You can't see this entity's registrations.	Ask an organization owner or admin for a role or scope that allows this action.

It can also return these common errors: api_version_unsupported, authentication_required, api_key_invalid, dry_run_not_supported, rate_limited, internal_error.

At a glance#

Request#

Path parameters#

Query parameters#

Response#

Examples#

Two consumers of a blocked OSS registration#

Errors#