What if only one spouse owes the tax?

When only one spouse owes the tax the IRS will allocate joint expenses, meaning expenses that cover more than one member of the household. The IRS will allocate these joint expenses based upon the percentage of household income earned by each spouse. For instance, if the husband owes the tax and he brings in 65% of the household income, the IRS will allow him 65% of the joint housing expense.
In order to calculate the expense allocation, the IRS will require the other spouse\’s income to be disclosed.
As far as the assets owned by both spouses jointly, it depends upon where the taxpayers live. If they live in one of the 41 separate property states, then the non-liable spouse only needs to share their income for the allocation, nothing more. If the couple lives in one of the nine community property states, then the non-liable spouse is required to provide all income and asset information because they may be liable for the tax debt under the community property laws.