# LinkCustomersToCertificate

Link customers to a certificate

`POST /api/v2/companies/{companyId}/certificates/{id}/customers/link`

**API:** AvaTax API
**Tag:** Certificates
**API Version:** v2
**Base URL:** https://sandbox-rest.avatax.com/
**Content-Type:** `application/json`
**Accepts:** `application/json`
**Authentication:** API Key (`Authorization` in header) or OAuth 2.0 or Basic (username + license key)

Source: https://developer.avalara.com/products/crossborder/api/methods/Certificates/LinkCustomersToCertificate/

## Description

Link one or more customers to an existing certificate.
            
Customers and certificates must be linked before a customer can make use of a certificate to obtain
a tax exemption in AvaTax.  Since some certificates may cover more than one business entity, a certificate
can be connected to multiple customer records using the `LinkCustomersToCertificate` API.
            
A certificate is a document stored in either AvaTax Exemptions or CertCapture.  The certificate document
can contain information about a customer's eligibility for exemption from sales or use taxes based on
criteria you specify when you store the certificate.  To view or manage your certificates directly, please
log onto the administrative website for the product you purchased.
            
Before you can use any exemption certificates endpoints, you must set up your company for exemption certificate data storage.
Companies that do not have this storage system set up will see `CertCaptureNotConfiguredError` when they call exemption
certificate related APIs. To check if this is set up for a company, call `GetCertificateSetup`.  To request setup of exemption
certificate storage for this company, call `RequestCertificateSetup`.

### Security Policies

* This API requires one of the following user roles: AccountAdmin, AccountOperator, AccountUser, AvaTaxOnlyAccountAdmin, AvaTaxOnlyAccountUser, AvaTaxOnlyCompanyAdmin, AvaTaxOnlyCompanyUser, BatchServiceAdmin, CompanyAdmin, CompanyUser, CSPTester, SSTAdmin, TechnicalSupportAdmin.
* This API depends on the following active services:*Required* (all):  AvaTaxPro, ECMEssentials, ECMPro, ECMPremium, VEMPro, VEMPremium, ECMProComms, ECMPremiumComms.

## Parameters

| Name | Type | In | Required | Description |
|---|---|---|---|---|
| `companyId` | integer | path | Yes | The unique ID number of the company that recorded this certificate |
| `id` | integer | path | Yes | The unique ID number of this certificate |
| `X-Avalara-Client` | string | header | No | Identifies the software you are using to call this API.  For more information on the client header, see [Client Headers](https://developer.avalara.com/avatax/client-headers/) . |

## Request Body

**Schema:** `LinkCustomersModel`

Represents a customer to whom you sell products and/or services.

| Property | Type | Required | Description |
|---|---|---|---|
| `customers` | string[] | No | An array of customerCodes that are exempted by this certificate |

## Responses

| Status | Description | Schema |
|---|---|---|
| 200 | Success | `CustomerModelFetchResult` |
| 400 | Bad Request | `ProblemDetails` |
| 401 | Unauthorized | `ProblemDetails` |
| 404 | Not Found | `ProblemDetails` |

### 200 Response: `CustomerModelFetchResult`

| Property | Type | Required | Description |
|---|---|---|---|
| `@recordsetCount` | integer | No |  |
| `value` | CustomerModel[] | No |  |
| `@nextLink` | string | No |  |
| `pageKey` | string | No |  |

## Example Request

```bash
curl -X POST "https://sandbox-rest.avatax.com/api/v2/companies/{companyId}/certificates/{id}/customers/link" \
  -H "Authorization: Basic <credentials>" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -d '{
  "customers": [
    "123456789"
  ]
}'
```