A standard deduction is a fixed amount that taxpayers can deduct from their taxable income without itemizing their deductions. For California Resident Income Tax Return, the standard deduction amount varies depending on the taxpayer's filing status. Itemized deductions are specific expenses that taxpayers can deduct from their taxable income, such as mortgage interest, state and local taxes, and charitable contributions. Taxpayers can choose to take the standard deduction or itemize their deductions, but they cannot do both in the same tax year.