Joint and Separate Liability for Taxes Between Divorced Spouses
When a taxpayer files separately, it is clear who will bear the burden of any tax liability assessed by the IRS. However, it may not be as intuitive when a tax return is filed on behalf of two taxpayers.
If a joint return is filed, the liabilities linked to this return are held joint and several between both taxpayers. (Internal Revenue Code, IRC 6013(d)(3)). This means you are both on the hook for the entire tax liability, until it is paid or released.