Line 12 on Form 1040 is where you enter your deduction from adjusted gross income: either the standard deduction for your filing status or the total of your itemized deductions from Schedule A, whichever is larger. The number you put on Line 12 gets subtracted from your AGI to produce taxable income on Line 15, so every dollar on this line is a dollar the IRS does not tax.
Where Line 12 Sits on the Form
Line 12 falls between your AGI, calculated earlier on Form 1040, and your taxable income on Line 15. You pick one of two paths to fill it in. The standard deduction is a fixed amount tied to your filing status and requires no receipts or extra schedules. Itemizing means adding up specific qualifying expenses on Schedule A and carrying the total to Line 12. Most filers take the standard deduction because it beats their itemizable total; itemizing only pays off when those expenses add up to more than the standard amount you would otherwise get.
Form 1040-SR, the large-print version available to filers 65 and older, uses the same line structure and schedules as the standard Form 1040.1Internal Revenue Service. About Form 1040, U.S. Individual Income Tax Return
Standard Deduction Amounts for 2026
The IRS adjusts the standard deduction for inflation each year. For tax year 2026:2Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill
- Single: $16,100
- Married filing jointly: $32,200
- Head of household: $24,150
- Married filing separately: $16,100
If none of the age, blindness, or forced-itemizing situations below apply to you, one of these amounts goes straight onto Line 12.
Extra Standard Deduction for Age 65+ or Blindness
Taxpayers who are 65 or older, or legally blind, have long qualified for a small additional standard deduction on top of the base amount. That additional amount is adjusted annually for inflation and runs roughly $1,500 to $2,000 depending on filing status.
Starting with the 2025 tax year and running through 2028, the One Big Beautiful Bill Act added an enhanced deduction of $6,000 for qualifying seniors. A married couple filing jointly where both spouses are 65 or older can claim an additional $12,000. This stacks on top of both the base standard deduction and the existing additional deduction for age, so a single filer over 65 could put a total standard deduction well above $22,000 on Line 12 for 2026.
When You Can’t Take the Standard Deduction
A few groups have to itemize no matter what the math says. If you are married filing separately and your spouse itemizes, you must itemize too. Nonresident aliens generally cannot claim the standard deduction. In those cases, your Line 12 figure will always come from Schedule A.
What Goes on Line 12 If You Itemize
When your qualifying expenses beat the standard deduction, you report them on Schedule A and carry the total to Line 12.3Internal Revenue Service. Topic No. 501, Should I Itemize? The categories that drive most itemized returns:
State and Local Taxes
You can deduct state and local income taxes (or sales taxes, but not both) plus property taxes. The cap, set at $10,000 beginning in 2018, was raised substantially by the One Big Beautiful Bill Act. For the 2026 tax year, the SALT deduction limit is approximately $40,400 for single and joint filers, with the cap indexed at 1% annually. Married-filing-separately filers get half that amount. This is the single biggest reason some taxpayers who stopped itemizing after 2017 may want to run the numbers again.
Mortgage Interest
Interest on a mortgage used to buy, build, or substantially improve your primary or second home is deductible on the first $750,000 of qualifying debt ($375,000 if married filing separately). That limit, originally temporary under the 2017 tax law, has been made permanent. Starting in 2026, premiums for private mortgage insurance also qualify as deductible mortgage interest for eligible filers.
Medical and Dental Expenses
Medical costs are deductible only to the extent they exceed 7.5% of your AGI. If your AGI is $80,000, only expenses above $6,000 count toward Line 12.
Charitable Contributions
Donations to qualified charities remain deductible when you itemize, but 2026 brings a change: only the portion of your total charitable contributions above 0.5% of your AGI counts. For someone with $100,000 in AGI, the first $500 of donations yields no itemized deduction. Cash contributions to public charities are generally limited to 60% of AGI, and non-cash property donations face tighter caps.
A Charitable Deduction Even If You Take the Standard
New for 2026, filers who take the standard deduction can still claim a limited charitable deduction. Cash contributions to qualifying charities are deductible up to $1,000 ($2,000 for joint filers) without filing Schedule A. If you donate modest amounts regularly but don’t have enough other expenses to itemize, this puts a small benefit on the table that was not previously available.
Fixing a Wrong Line 12 After Filing
If you realize you picked the wrong deduction method or miscalculated your itemized total, you correct the return by filing Form 1040-X. You enter the original amounts in one column, the changes in a second, and the corrected figures in a third, with a written explanation. Both spouses must sign a joint amended return.4Internal Revenue Service. Instructions for Form 1040-X Amended U.S. Individual Income Tax Return
The deadline for claiming a refund through an amended return is generally three years from the date you filed the original return, or two years from the date you paid the tax, whichever is later. Processing takes 8 to 12 weeks, and sometimes up to 16. If the IRS finds the error before you do, the standard accuracy-related penalty is 20% of the underpayment.5Office of the Law Revision Counsel. 26 USC 6662A – Imposition of Accuracy-Related Penalty on Understatements With Respect to Reportable Transactions An isolated math error or honest reliance on a tax professional’s advice can qualify as reasonable cause for penalty relief, but you have to show you exercised ordinary care.
Records to Keep Behind Line 12
The documents supporting your Line 12 deduction need to outlive your filing by at least three years, which covers the standard audit window. If you underreported income by more than 25% of gross income, the IRS has six years. Claims involving worthless securities or bad debt require seven years of records.6Internal Revenue Service. How Long Should I Keep Records
If you itemize, hold on to mortgage interest statements, property tax bills, medical expense receipts, and charitable donation records for at least three years after filing. Charitable contributions of $250 or more require a written acknowledgment from the organization showing the amount and whether you received anything in return.7Internal Revenue Service. Charitable Contributions: Written Acknowledgments In an audit, send copies, never originals.8Internal Revenue Service. IRS Audits: Records We Might Request