There are several methods for managing the exempt status of your customers.
Exempt using Avalara CertCapture
CertCapture makes it easy to create, validate, store, manage, and retrieve sales tax exemption and reseller certificates and acts as aexemption certificates.
To begin using CertCapture:
Exempt using the Avalara Exemption Certificate Management System (ECMS)
The Avalara Exemption Certificate Management System (ECMS) is a free service included with each AvaTax account. However, unlike CertCapture, ECMS is not a system of record storing and managing exemption certificates. ECMS does not store the exemption certificates themselves, only data about the exemption certificates called exemption certificate entries. AvaTax uses the information to exempt appropriate transactions from sales tax, but you're still required to save physical or digital copies of valid exemption certificates on site.
To begin using ECMS:
Exempt using exemption certificate numbers
Use an exemption certificate number in OpenCart to exempt customers.
Exempt using entity/use codes
Exempt customers using the Entity/Use Code field within OpenCart and send that information to AvaTax using a pre-defined exemption code reason or a custom reason.
Once you've exempted the necessary customers, manage the taxability of your products and services.