Many many years ago, I did not have a tag (except the local dog license) on my first dog. Back then, I was young (well not really that young) and lived by myself and was afraid of putting my personal information on a dog collar where anyone could get that information. I figured that, a). everyone in the complex knew my little girl and knew where she lived, and b). if she got out somewhere else, whoever found her could identify her by calling the township, and they (the township) would contact me. However, I know of two dogs (not my own) who definitely benefitted from wearing tags, and have had ID tags on my dogs for years.