Hi Matthew! Plans that are subject to ERISA laws must file a form 5500. According to the Department of Labor's website, ERISA is "a federal law that sets standards of protection for individuals in most voluntarily established, private-sector retirement plans." Going by that definition, government entities do not qualify for ERISA and therefore do not have to file a form 5500.
There are forms and plan documents that still must be submitted. Start with your retirement plan website and look for the "plan document." You kind find a lot of information there.