Insperity is one such company--my clients typically have employees in multiple states and we just handle all the details for them. https://www.insperity.com/bpa/zac.mutrux
Multi-state employment can be quite complex and a lot of startups are struggling with it. I work for a company called Insperity that completely solves this problem (full stop) by taking on full responsibility for payroll taxes and a lot of HR related compliance issues. Some of our success stories include Netflix, Trulia, Workday, Buzzfeed, Hello Fresh etc. Anyone curious about this platform that enables remote work in any state is free to drop me a line--happy to discuss. [email protected]