Calculate your monthly gross income. HUD includes and excludes certain types of income and assets when calculating how much you make. Contact your PHA for specifics or refer to HUD's website (see Resources). Generally, HUD counts money you receive from a job or through public assistance, Social Security or disability as income.
Determine HUD's fair market rent for the unit size you wish to rent in your area. Again, your PHA can provide you with this information or you can access it at HUD's website. If the unit you want to rent is at or below HUD's fair market rent, calculate 30 percent of your monthly gross income; this is the amount you must put toward your rent. For example, HUD sets the fair market rent for a one-bedroom apartment in the Columbus, Ohio, metro area at $616, as of 2011. If you want to rent a $600 one-bedroom and you earn $1,000 a month, you'll have to pay $300 a month in rent ($1,000 x .30, or 30 percent); your PHA pays the remaining $300.
Factor in any rent that exceeds HUD's fair market rent figure. HUD requires Section 8 tenants to cover these excess amounts, however, it does not allow a Section 8 household to put more than 40 percent of its income toward housing. For instance, if you wish to rent a $750 one-bedroom in Columbus, you would have to pay $300 (30 percent of your $1,000 income) plus $134, which represents the amount over HUD's $616 fair market rent. This brings you total share of the rent to $434, equal to 43.4 percent of your earnings. Your PHA will not allow you to rent a unit at this level via the Section 8 program.