Do you report it

[greyboy39]

Wires terminating into an electrical main panel and not connected. Does it make a difference if wire nuts are installed? If so, is their a code cite you reference? I always have and basically stated no foreign objects in panel..but have never actually seen a code prohibiting it.

[Marc]

I don't report it.  I don't see how it's a problem.

[Jim Katen]

I don't know of any code that prohibits it, though one could argue that 408.4 requires them to be labeled. (. . . it might be a weak argument.) 

If the wires or cables are neatly tucked in the back of the panel, labeled as to where they go, and cleanly clipped at the ends, I don't say anything about them. (I have cables like this in my own house. One goes to a j-box in the attic and one goes to a j-box in the basement - as future proofing.)

If the wires have their insulation stripped back so that the conductors are exposed, I suggest trimming them and adding wire nuts as well as figuring out where they go and labeling them. 

[Nolan Kienitz]

When my SEP was replaced a few years ago I had several "spare" circuits routed in our home (as Jim noted) for future proofing.

Not terminated in panel, but labeled.

I also have 4 extra/spare breakers plugged in, but not yet wired. Also labeled. More future proofing.

Electrician who changed out my panel had recommended the future planning for the "just in case" times.