This chart is designed to summarize the top fifteen programs that benefit from "tax expenditures." A Tax Expenditure is a concession from the income tax designed to benefit an industry or activity, much as a direct appropriation of federal funds would. Tax expenditures (deductions, exemptions, credits, breaks) represent government spending for targeted activities, by allowing entities pursuing those activities to pay lower (or no) taxes. By law, the President must calculate how much tax expenditures cost each year. Exclusion of employer contributions for medical insurance premiums is the number one expenditure function costing $113 billion. Second was deductibility of mortgage interest on owner-occupied homes, costing $70 billion.