I want to use a Certified Service Provider (CSP), but I'm not registered through the STreamlined Sales Tax Registration system (SSTRS). What do I do?
Answer:   If you are interested in contracting with a CSP, contact the CSP to discuss their services before you register.  Once you are under contract with the CSP, the CSP can register your company through the SSTRS.

You may register through SSTRS even if you are already registered in some of the Streamlined states.