when it comes to budgeting your monthly expenses, there are general guidelines you're supposed to follow. the most basic of those general guidelines is trying not to budget more than a third of your take home pay on rent. you should not be shelling out more than a third of what is left over after taxes on keeping a roof over your head. that's the idea, anyway. the new study out this week reports more than 21 million households are paying at least 30% of their income and in many cases much more than that on shelter. that is the highest percentage on record. some people in families can't afford to do that, but many cannot. families facing those kinds of rent burdens tend to cut way back on other basic necessities, things like food and health care. lowest income households were said to shrink their food budge hes by $130 a month.