Retroactive SAG stipulations
 

If I shot a film with an actor, who joined SAG after principal production, do I need to sign an experimental film agreement in order to use the actor's services for post-production, say dubbing? I have a dated release.

It seems to be that it depends entirely on what your original contract with the actor stated. If in the original contract (before he was a SAG member) covered him coming back to do dubs, then I would imagine no. However, if having him come back to do dubs means contracting him for additional work that was not under the original agreement, then yes, you probably will need to get the expirimental film agreement.