This is a case-by-case decision. It is certainly an issue to consider if you are contemplating divorce or already in the midst of a divorce.
It is true that a joint return will usually produce a lower tax than if the two spouses filed separately.
However, there is a downside to filing a joint return – joint and several liability. In other words, the IRS can come after either spouse for the entire tax owed. So, if your spouse is self employed and you do not have a good understanding of the operation of his/her business maybe you should think thrice about filing a joint return. Or, if there is something that just does not “smell right” then avoid the joint return.
Innocent spouse protection is sometimes available but, unfortunately, not nearly as often as people think.
Remember, filing a joint tax return is a choice. Both spouses elect to this tax filing status. But, once you file a joint return there is no turning back. While you are allowed to amend your return (adjust numbers, deductions etc.) you are not allowed to change your tax filing status. Just like many choices in the context of a divorce there are no “do overs.”
Read an example below of what can happen if you make the wrong choice.
Joint Return for Divorcing Spouses – Think Thrice – Then Think Agai n – Forbes