The standard deduction is the amount of income the government does not tax at all, available to everyone without receipts or paperwork. For 2026 it is $16,100 for single filers and $32,200 for married couples filing jointly, with slightly higher amounts for people 65 and older or blind. You subtract it from your income, and only what is left is sorted into tax brackets.
The alternative is itemizing: adding up specific expenses like mortgage interest, state and local taxes (up to a cap), charitable gifts, and large medical bills, and deducting that total instead. You take whichever is larger. Since the standard deduction roughly doubled in 2018, most households come out ahead with the standard amount, and only about one in ten itemize.
A quick example: a single renter earning $90,000 with $3,000 of charitable gifts and $6,000 of state tax has $9,000 of itemizable expenses, well under $16,100. The standard deduction wins and taxable income is $73,900.
The common mistake is assuming a mortgage automatically means itemizing. A married couple would need more than $32,200 of combined deductions to beat the standard amount, which takes a large mortgage, a high-tax state, or both. Another is forgetting that deductions reduce taxable income, not tax owed: a $1,000 deduction saves $220 for someone in the 22% bracket, not $1,000.