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

# Exemption Certificates

> Manage exemption certificates for a customer.

## Overview

Exemption certificates are legal documents that allow specific buyers to purchase goods or services without paying sales tax. Merchants can use Commenda to create and manage exemption certificates for their customers.

## How to create an exemption certificate

To create an exemption certificate, follow these steps:

1. **Create a Customer Record:** Use the customer endpoint to create a customer record, which will be linked to the exemption certificate. Save the `customer ID` from the response. Learn more about customer creation [here](/engine/indirect-tax/customers/customer).

2. **Upload the Certificate File:** Use the file endpoint to upload the exemption certificate document and save the returned file ID. Details on how to use the file endpoint can be found [here](/engine/indirect-tax/files/files).

3. **Link Customer and File:** Use the `POST /exemption-certificates` endpoint to link the customer and the uploaded file, thereby creating the exemption certificate.

## Certificate types

1. **Single state**: This type of exemption certificate is valid only within a single state. Each state has specific rules regarding which entities can claim exemptions and the process for doing so.

2. **SST**: This is a [Streamlined Sales Tax exemption certificate](https://www.streamlinedsalestax.org/Shared-Pages/exemptions-). It may be recognized in multiple states, including any states that are members of the Streamlined Sales Tax Governing Board.

3. **MTC**: This is a [Multistate Tax Commission exemption certificate](https://www.mtc.gov/resources/uniform-sales-use-tax-exemption-certificate). It may be recognized in multiple states, including any of the 36 states which are are part of the Multistate Tax Commission.

## Certificate review status

Exemption certificates include a `verification_status` field so Commenda can surface the review state of a certificate. When a certificate is created with a `file_id`, its initial status is `VERIFICATION_PENDING`. Certificates created without a file are marked `NOT_READY` until a file is attached.

Tax calculation is based on active jurisdiction exemptions, effective dates, and expiration settings. Do not use `verification_status` alone to predict tax treatment. If Commenda marks a certificate `VERIFICATION_FAILED`, the certificate's jurisdiction exemptions are deactivated.

When Commenda updates a certificate to `VERIFICATION_SUCCESS` or `VERIFICATION_FAILED`, the corresponding exemption certificate webhook is sent. For more details, see [exemption certificate webhooks](/engine/indirect-tax/webhooks/event#exemptions-certificates).