Some systems allow tax deductions for certain nonbusiness expenses (sometimes called personal or domestic expenses).[6] Such outlays may include personal expenses, such as a home mortgage interest deduction, and vary widely by jurisdiction. In addition, many systems only levy taxes on earnings above an income tax threshold, allow deductions for personal allowances or a minimum deemed amount of personal deductions. The United States federal tax system allows a deduction for personal exemptions, as well as a minimum standard deduction in lieu of other personal deductions.