A tribal government can't have a 401(k) for employees providing government services (such as K-12 school employees, police and fire employees, courthouse employees, etc.), but it can have a 403(b) for some of those employees (e.g., the school employees). It also can have a governmental profit sharing plan for these employees with a pre-tax pick-up by the tribe of mandatory employee contributions, which mimics a 401(k) plan to a great extent. Those options apply to the tribe employees providing government services because the tribe is treated like a state government employer with respect to those employees. It can have a 401(k) for its employees providing commercial services (such as casino workers) because it's treated like a private employer with respect to employees providing non-governmental/commercial services.