The first step when using Layer is to onboard your customer to Layer using the Create a business endpoint. This endpoint creates the record for your customer in Layer’s systems. There are many optional features, such as specifying external accounts connected via Plaid. The Create a business endpoint lists the full set of options.
Request
curl -X POST https://sandbox.layerfi.com/v1/businesses \
  -H "Authorization: Bearer <access_token>" \
  -H "Content-Type: application/json" \
  -d '{
    "external_id": "test-acme-id",
    "legal_name": "ACME LLC",
    "tin": null,
    "us_state": "CA",
    "entity_type": "LLC",
    "phone_number": "+18005555555",
    "unit_ids": [{"unit_id": "111111"}]
  }'

​
Plaid credentials

If you’ve added Plaid credentials (see Plaid Configuration), link Plaid accounts by including Plaid item ids & access tokens in the plaid_items field. 
"plaid_items": [
	{ "item_id": "item-id-1", "access_token": "access_token_1" },
	{ "item_id": "item-id-3", "access_token": "access_token_3" }
]
The Layer API will respond with the created Business object. Within the object will be a unique id, which you will use to make calls on behalf of the business in subsequent steps.
Response
{
  "data": {
    "id": "863ed926-e30d-40f4-8e7e-b0d5387ce4fb",
    "type": "Business",
    "external_id": "test-acme-id",
    "legal_name": "ACME LLC",
    "tin": null,
    "business_activity_code": null,
    "us_state": "CA",
    "entity_type": "LLC",
    "phone_number": "+16504651359",
    "naics_code": null,
    "imported_at": "2023-06-15T22:12:05.467940Z",
    "updated_at": "2023-06-15T22:12:05.467940Z",
    "archived_at": null,
    "unit_accounts": [
      {
        "id": "111111",
        "imported_at": "2023-06-15T22:12:05.467940Z"
      }
    ]
  },
  "meta": {}
}