[kentonv]

I think we understand that an auditor could, in theory, do that, but the question is whether auditors do, in practice, do it. The IRS is not supposed to be screwing people on technicalities like this, and a reasonable auditor should conclude that the spouse obviously would have signed had they known they needed to. Regulation isn't interpreted by computers, it is interpreted by humans who can make reasonable adjustments for these sorts of mistakes.

So, does anyone known of someone who actually got screwed by this in an audit? I'm sure it has happened often enough that at least someone out there has been audited who would be affected.