This type of question might be related to the affordable care act health insurance subsidy, or to certain state tax credits and benefits. For the ACA, your household includes your spouse, dependents and some others. Their income is used along with yours to determine eligiblity for the credit, even if the income is not taxable on your return.https://www.healthcare.gov/income-and-household-information/household-size/
For state tax credits, you would have to look up the rules for that credit in that state.
