A rough estimate for calculating HUD rent: For the last 12 month period add up all household income, including income from assets (interest/income from checking accounts, savings accounts, stocks, bonds, insurance policies, real estate, etc.). Subtract from that income amount the household out-of-pocket medical expenses paid for that same 12 month period. Then, multiply that amount by 30% (.30), divide by 12 (12 months), and that amount should be a close estimate of your monthly rental.