You want to know the difference between a Streamlined Sales Tax (SST) Model 1 and Model 4 seller.
SST Model 1 Certified Service Provider (CSP)
An agent certified under the SSUTA to perform all the seller's sales and use tax functions, other than the seller's obligation to remit tax on its own purchases. A CSP is designed to allow a business to outsource most of its sales tax administration responsibilities. The software system of a CSP identifies which products and services are taxable, applies the appropriate tax rate, interfaces with your accounting system, and files the tax return and remits the tax to the appropriate taxing authority. Each member and associate state has certified the accuracy of the software and provides liability relief for errors that may result in the incorrect calculation of the tax amount (the CSP can provide additional information regarding their relief.)
The model 1 Volunteer seller is not charged a filing fee. Avalara receives compensation from the state that equals a percentage of the tax collected. This compensation from the SST states to Avalara is labeled as CSP fee on the Liability Worksheet and, again, is paid by the state, not the Model 1 seller.
SST Model 4 – Other
A seller that registers with the Streamlined Sales Tax program and chooses to calculates its tax on its own or using AvaTax, prepares its own tax return, or engages Returns to process and file the tax returns on their behalf. A Model 4 seller is not contracted with Avalara to preform Streamlined Sales Tax CSP services.
For more information on Streamlined Sales Tax, see Avalara’s Streamlined Sales Tax – Frequently Asked Questions.