I don't think there is. I think FFP applies to the PL and Championship. Salary Cost Management Protocol (SCMP) applies to League 1 & 2. Not sure there's anything below that. At a practical level I guess it would be harder to police given the number of clubs, reporting and monitoring requirements, and finer margins the lower you go.
I'm pretty sure Billericay would be drawing a lot of attention if it did apply!