As a former IRS Agent, this question comes up often, Do both husband and wife half to sign their personal income tax return?
A deficiency assessed on a joint account based on the signature of only one spouse is generally not a valid assessment with respect to the non-signing spouse. This also applies if the spouse did not sign an amended return. There can be a binding joint return even if one spouse failed to sign the return, if the parties’ intended to file a joint return. Thus, one must examine the parties intentions to ascertain whether the absence of one signature invalidated the return.
See financial v. Commissioner, 34 T.C. 740 (1960), aff’d, 325 F.2d 1 (2 d. Cir.1963).
If an invalid assessment was made against a non-signing spouse, the IRS may not be able to assess the proper amount against the non-signing spouse because the statute of limitations may have expired.