Dorothy - You are right! It is recommended (not required) that you store your I-9s in a binder separate from the employee file. It's easier to access if you get audited or need to purge any.
Robin Throckmorton Absolutely agree. Not trying to muddy the waters - but we have seen some prefer to "store electronically" and our attorney approved this as long as the files were password protected. However, you need to be prepared for an audit AND be sure to keep your review/purge process going. :)
Melanie Booher Excellent points, and also keep in mind that if you are doing electronic I-9s through your HCM, make sure that you are also downloading them in the event that you ever leave and need to get your data back out of the system!