Updated October 17, 2026. Quick answer: Line 21 is the student loan interest deduction, figured on a worksheet in the Form 1040 instructions. Line 22 is reserved for future use and takes no entry. Line 23 is the Archer MSA deduction, and the instructions send you to Form 8853 for it.
IRS worksheets from the 2025 Form 1040 instructions, read line by line: Student Loan Interest Deduction Worksheet.
Line 21: who can take the deduction
The form’s caption reads “Student loan interest deduction”. The instructions begin: “You can take this deduction only if all of the following apply.” The conditions that follow include these:
- “You paid interest in 2025 on a qualified student loan (defined later).”
- “Your filing status is any status except married filing separately.”
- “Your modified adjusted gross income (AGI) is less than $100,000 if single, head of household, or qualifying surviving spouse; $200,000 if married filing jointly.”
- “You, or your spouse if filing jointly, aren’t claimed as a dependent on someone else’s (such as your parent’s) 2025 tax return.”
Where the line 21 number comes from
The instructions say “Use the worksheet in these instructions to figure your student loan interest deduction.” That is the Student Loan Interest Deduction Worksheet for Schedule 1, line 21, and this page does not copy its cells. One exception sends you elsewhere: “Use Pub. 970 instead of the worksheet in these instructions to figure your student loan interest deduction if you file Form 2555 or 4563, or you exclude income from sources within Puerto Rico.”
The worksheet starts with the total interest you paid in 2025 on qualified student loans. The boxes on the interest statement you may receive are explained on the page about Form 1098-E boxes 1 and 2.
What counts as a qualified student loan
The instructions define it this way: “A qualified student loan is any loan you took out to pay the qualified higher education expenses for any of the following individuals who were eligible students.” On the expenses they say “Qualified higher education expenses generally include tuition, fees, room and board, and related expenses such as books and supplies.” One more rule covers tuition programs: “Don’t include any amount paid from a distribution of earnings made from a qualified tuition program (QTP) after 2018 to the extent the earnings are treated as tax free because they were used to pay student loan interest.”
Line 22: reserved for future use
The form’s caption reads “Reserved for future use”. The instructions say “Line 22 has been reserved for future use.”
Line 23: Archer MSA deduction
The form’s caption reads “Archer MSA deduction”. The instruction for the line is short: “See Form 8853.” Form 8853 is also the source of an income line earlier on the schedule, covered in Schedule 1 lines 8d to 8f. For a related health account deduction, see the page on Form 8889.
Where it goes next
Lines 21 and 23 are added on line 26, whose caption reads “Add lines 11 through 23 and 25. These are your adjustments to income.” The sum then goes “Enter here and on Form 1040, 1040-SR, or 1040-NR, line 10”. See lines 25 and 26 and the Schedule 1 (Form 1040) page.
Edition and line numbers
This page reads the 2025 Schedule 1 (Form 1040) and the 2025 Form 1040 instructions, the current files irs.gov served on 2026-10-17. They are the files for the tax year 2025 return, filed in 2026. The schedule says “Attach to Form 1040, 1040-SR, or 1040-NR.” Schedule 1 has no separate instructions booklet. Its line instructions sit inside the Form 1040 instructions, under the heading “Instructions for Schedule 1”. Check the tax year printed on the schedule you are filling in and use the line numbers on that year’s schedule, because a different year’s schedule can number or word its lines differently.
Common mistakes
- Claiming the deduction on a married filing separately return. The instructions say “Your filing status is any status except married filing separately.”
- Entering something on line 22. The instructions say “Line 22 has been reserved for future use.”
- Figuring the Archer MSA deduction without Form 8853. The instruction for line 23 is “See Form 8853.”
Related: Form 1098-E boxes 1 and 2, Form 8889, and Form 1040.
Sources
- Instructions for Form 1040 and Form 1040-SR (2025): https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
- Schedule 1 (Form 1040), Additional Income and Adjustments to Income (2025): https://www.irs.gov/pub/irs-pdf/f1040s1.pdf
Read from the IRS documents linked above on October 17, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.