Write-offs you are permitted to subtract from your gross income to calculate your taxable income. All taxpayers may claim a standard deduction, which is determined by the IRS. If your qualifying expenses exceed your standard deduction, you may claim the higher amount by itemizing your deductions. Although no records are needed to back up your right to the standard deduction, you must maintain records of qualifying expenditures if you itemize. For higher income taxpayers, the amount of their otherwise allowable itemized deductions will be reduced when adjusted gross income (AGI) exceeds a threshold amount. The reduction and threshold amounts can vary each year.