If you want to find a good determining factor for the cost of living and the general affordability of housing in Thousand Oaks, CA, all you must look at is the percentage of monthly income that should be spent on housing expenses, otherwise known as the debt-to-income ratio (DTI). Generally speaking, no more than 28 percent of your total gross income should be spent on your housing expenses and not more than 36 percent of your gross income on total expenses, including debts. In Thousand Oaks, CA, the median monthly income is $114,155 for those who own their own homes. Under the standard rule, that income level would allow for $2,663 to be budgeted for housing expenses each month, at the most. Renters, on the other hand, earn about $65,885, per the median income in the area. That would allow for renters to spend up to $1,537 on monthly rental expenses.