If you are referring to Section 8 housing, it is HUD. You would apply with the state;
Am I eligible?
Eligibility for a housing voucher is determined by the PHA based on the total annual gross income and family size and is limited to US citizens and specified categories of non-citizens who have eligible immigration status. In general, the family's income may not exceed 50% of the median income for the county or metropolitan area in which the family chooses to live. By law, a PHA must provide 75 percent of its voucher to applicants whose incomes do not exceed 30 percent of the area median income. Median income levels are published by HUD and vary by location. The PHA serving your community can provide you with the income limits for your area and family size
I hope that helps!