a spouse is not legally supposed to file a joint return without the content of the other. This is a crime.
An individual may not file a joint tax return without the consent of the marital partner. Filing a joint tax return without the consent of the marital partner is a crime. Similarly, signing your name on the return without your consent is considered forgery, which is also a crime. If a joint return was filed without your consent, the IRS will automatically deem the non-consensual joint tax return to be fraudulent.
If the IRS decides that your spouse filed the joint return intentionally and without your consent, she may face hefty financial penalties.
In addition, if the IRS decides that your spouse filed the joint return intentionally and without your consent, your spouse may have to go to jail.
however a court found the above not to be the case.here's a summary
The district court held that the joint returns were valid. The court said there is a limited exception to the rule requiring both signatures: when only one spouse signs a joint return, the return is valid if the non-signing spouse intended to file jointly. "The intent to file jointly may be inferred from the acquiescence of the non-signing spouse." Therefore, "where a husband files a joint return without objection of the wife, who fails to file a separate return, it will be presumed the joint return was filed with the tacit consent of the wife."
