First a note about charitable solicitation and commercial co-venture laws:
Not all states require nonprofits to register their fundraising efforts. I am not a legal expert, FYI. That being said, legally commercial co-venture laws are different, generally requiring much less documentation than what is required for charitable solicitors.
Professional Solicitors, for example, are required to register, which often involves fees, in all but 6 states and the District of Columbia.
Commercial co-venturers, which is the category most cause marketers fall into (as of 2017) are required to file and report in only a handful of states, including Alabama, California, Hawaii, Massachusetts, Mississippi, and South Carolina among them.
To learn more about charitable solicitations, take a look at this IRS article.