I keep hearing people say "We don't have any real definition of affordable housing." Yes we do. It's been in place for some decades now. Your housing is not affordable if you have to pay more than 30% of your income to cover the costs of your housing. Your housing is affordable if you are paying 30% or less of your income towards your housing costs. (See documents referenced below.) (1, 2)
Example: you are a single mom who works as a medical assistant. Your salary is $36,000. To be affordable, your rent should be $900 a month or less. Good luck because in Marin, the average one bedroom apartment is $2,297.(3)
"Families who pay more than 30 percent of their income for housing are considered cost burdened and may have difficulty affording necessities such as food, clothing, transportation and medical care. An estimated 12 million renter and homeowner households now pay more than 50 percent of their annual incomes for housing. A family with one full-time worker earning the minimum wage cannot afford the local fair-market rent for a two-bedroom apartment anywhere in the United States."(4)
So, the goal for many subsidized units for low and very low-income renters is to charge no more than 30% of that tenant's income.
Here is some research from HUD on this issue:
2) This paper argues that the 30% figure is actually probably too high because low-income households end up with other costs related to long commutes and security that add to their housing costs: http://fanniemae.com/…/hoytpivo_mfhousing_affordablehousing…
3) Marin rental prices: http://www.marinapartments.com/_docs/RentalSurvey.pdf
4) HUD definition: http://portal.hud.gov/hudportal/HUD…