“Itemizing” means listing eligible individual expenses on a tax form or schedule instead of taking the standard deduction. The practical idea is simple: if your eligible deductible expenses (mortgage interest, certain medical expenses above thresholds, state and local taxes up to limits, charitable contributions, casualty losses in specific cases, etc.) add up to more than the standard deduction available to you, itemizing generally yields a lower taxable income. But itemizing requires recordkeeping and often additional forms — receipts, statements, mortgage 1098 forms, giving acknowledgements for charity, and medical bills. The burden of proof rests on the taxpayer: without receipts or proper substantiation some itemized claims may be disallowed in an audit. For many taxpayers, the standard deduction is larger or simpler, so they pick it and avoid extra paperwork. However, life events — buying a home, major unreimbursed medical costs, or large charitable giving — can push a taxpayer toward itemizing. If you’re planning to itemize, collect documentation throughout the year and store it in an organized way (digital scans work well).

When evaluating itemizing versus the standard deduction, run a simple comparison: total your potential itemizable expenses and compare to the standard deduction amount you would otherwise claim. Don’t forget less obvious items: out-of-pocket medical costs above the allowed threshold, state and local taxes (subject to stated limits), unreimbursed casualty losses, and certain miscellaneous deductions if allowed in your jurisdiction. Note that some itemized categories have limits or phase-outs; for example, only the portion of medical expenses above a set percentage of adjusted gross income may be deductible. Also consider timing: bunching deductible expenses into one year (for example, prepaying charitable contributions or medical procedures) can push you into an itemizing year and make itemizing advantageous, then standard-deduction in other years. If you expect to alternate between itemizing and standard deduction, tracking and maintaining good documentation still matters. Finally, check whether your filing software or preparer automatically compares both routes — many modern tax tools will compute both the standard deduction and itemized totals and recommend the better option.