Which household configuration creates only one tax household?

The scenario involving married couples filing jointly with dependents creates only one tax household because a married couple who files jointly combines their incomes and deductions on a single tax return. This simplifies the tax household structure, as both spouses and their dependents are considered part of one unit for tax purposes. When a couple files jointly, they effectively share tax responsibilities and benefits, which reinforces the notion of a singular tax household.

In contrast, other household configurations like single parents with dependents or domestic partners filing separately can result in multiple tax households. For single parents, each parent may claim their own dependent(s), creating separate tax households. Similarly, domestic partners filing separately do not combine their incomes or tax benefits, thus establishing different tax households. Roommates, while they may share expenses, typically do not file joint tax returns and also do not constitute a single tax household.