You're absolutely right.  The form instructions are not authoritative, and in most cases there is no penalty for not complying unless the issue is also addressed by something more authoritative like the Code, Regs, etc.. I'm intrigued to find out that many people have been switching the names for years and it hasn't created any problems with the IRS.  That was always my main concern....that the client would receive a notice as a result of some strange working of the IRS matching system.  I would then have to take time to resolve the issue over something as simple as which name is first on the return.