How do I move a toilet over approximately 18 inches?

We will get you over to plumbing so a few real plumbers can help. In general, you must access your drain, cutting out the current closet bend and then extend a new piece of pipe to where you want it located. Either the floor must be opened or access from below, which are you willing to do?

Cajunbedbug

Ballenger gave you straight forward answer. We just need to know what the pipes are made of and how accessible the pipes are to tell you more.

Let us know... O.K.

MARK