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Official form guide
Form 1040S1: 1040 (Schedule 1)
IRS Form 1040S1 is an attachment to Form 1040, 1040-SR, or 1040-NR that reports additional income and adjustments to income for the year 2025. For 2025, enter amounts reported on Form(s) 1099-K included in error or for personal items sold at a loss.
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IRS Form 1040S1 - 1040 (Schedule 1)
IRS Form 1040S1 is an attachment to Form 1040, 1040-SR, or 1040-NR that reports additional income and adjustments to income for the year 2025. For 2025, enter amounts reported on Form(s) 1099-K included in error or for personal items sold at a loss.
Risk Radar
Scan points- 1Ensure you correctly combine lines 1 through 7 AND line 9 to calculate your total additional income for Line 8.
- 2Failing to report all 1099-K amounts correctly in Part I
- 3Omitting the total other income calculation from lines 8a through 8z (Line 9)
- 4Not transferring the final combined totals from Line 10 onto Form 1040, 1040-SR, or 1040-NR
- 5Forgetting to attach supporting schedules like Schedule C or Schedule E when applicable
Plain English
This form helps you report extra money you earned or deductions that reduce your taxable income beyond what is already listed on your main tax return. It collects details about various types of earnings, from business profits to investment gains and specific adjustments like educator expenses. By completing this, you ensure the IRS has a complete picture of your 2025 financial activity.
Submission Date
- Filing date: 2026-01-02 11:10:41
- Preparation window: collect IDs, supporting records, and signatures in advance.
- Final review: verify names, dates, and required fields before submission.
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What this form is for
- Use this form when reporting additional income or adjustments to income that must be attached to Form 1040, 1040-SR, or 1040-NR for the year 2025.
- Do not use it when all of your additional income and adjustments are already reported directly on one of the main lines of Form 1040 without needing to attach this schedule.
- Check Schedule C (Form 1040) instead when reporting business income or loss from a sole proprietorship.
Form selector
Use this form or another form?
Rental real estate, royalties, partnerships, S corporations, trusts, etc.
This schedule is used for income/losses derived from these types of properties or entities.
✓ Check before you continue
Farm income or loss
Use this form to report income or losses generated from farming activities.
✓ Check before you continue
Business expenses of reservists, performing artists, and fee-basis government officials
This specific attachment is required to detail certain allowable business deductions for these groups.
✓ Check before you continue
Deadline or filing window
The Form 1040S1 is used for the 2025 tax year. While a specific filing deadline date is not listed, it must be filed with the main return by the applicable due date. No extension dates are stated on this form, but instructions direct users to www.irs.gov/Form1040.
Checklist
What you need before filling it out
Name(s) shown on Form 1040, etc.
Name(s) from your return · Part I/II Header (p.1/p.2)
Amount for 1099-K errors/losses
Amount reported on Form 1099-K · Part I, Line 1
Business income or (loss)
Total from Schedule C · Part I, Line 3
Health savings account deduction
Amount detailed on Form 8889 · Part II, Line 13
Total other adjustments
Sum of lines 24a through 24z · Part II, Line 25
Before you submit
- 1Verify the name(s) listed on this Form 1040S1 match those on your primary return.
- 2Confirm you have entered the correct amount from Form(s) 1099-K for errors or personal sales losses into Line 1.
- 3Ensure all income items (Lines 1 through 7, and lines 8a through 8z) are correctly totaled onto Line 10.
- 4Check that the total adjustments to income (Line 26) accurately reflects Lines 11-23 plus Line 25.
- 5Verify that any required attachments (like Schedule C or Form 8889) are included with this form.
- 6Confirm you have calculated and entered the final combined amount on Line 10, ready for Form 1040.
- 7Double-check that Part II adjustments correctly account for items like Educator expenses (Line 11) or IRA deduction (Line 20).
How to file this form
- 1Complete all required fields on Schedule 1 (Form 1040), beginning with your name and SSN.
- 2Calculate the total of Part I, Lines 1 through 7 plus Line 9 to determine your Additional Income for Line 10.
- 3Determine your Adjustments to Income by summing Part II, Lines 11 through 23 and Line 25, then enter this total on Line 26.
- 4Attach Schedule 1 (Form 1040) to Form 1040, 1040-SR, or 1040-NR before mailing it for official processing.
Known limitations
- 1The amounts reported to you on Form(s) 1099-K that are *not* included in error or for personal items sold at a loss should be reported elsewhere on the return depending on the nature of the transaction (Instructions p.1).
- 2Not all income types must be listed under Part I; some, like rental real estate, require attaching Schedule E (Instructions p.1).
- 3Certain adjustments to income, such as educator expenses or moving expenses for military members, require attaching a specific supporting form (Instructions p.2).
Field map
Compact field-by-field guide
Personal Info
3 items
Enter your legal first and last name as shown on your Social Security card.
Your SSN must match IRS records exactly.
Current mailing address including street, city, state, and ZIP code.
Filing Status
1 items
Select: Single, Married Filing Jointly, Married Filing Separately, Head of Household, or Qualifying Surviving Spouse.
Income
1 items
Sum of all income sources — wages, interest, dividends, business income, capital gains, unemployment, retirement, and other income.
Adjustments
1 items
Total income minus above-the-line deductions such as IRA contributions, student loan interest, and HSA contributions.
Deductions
1 items
Choose the higher of the standard deduction for your filing status or total itemized deductions from Schedule A.
Tax
1 items
AGI minus deductions. This determines your tax bracket and the amount of tax owed.
Payments
1 items
Sum of federal tax withheld, estimated tax payments, and refundable credits like the Child Tax Credit.
Signatures
1 items
You must sign and date the return. Unsigned returns are invalid.
Almost done reviewing the fields?
Fillable formOpen in Editor->The current edition is 20/25, and users should go to www.irs.gov/Form1040 for instructions and the latest information.
What changed or needs a fresh check
- Edition date — confirm the revision reads 20/25.
- Form Number — confirm the form number is correctly listed as Schedule 1 (Form 1040).
- Mailing address — Not stated in the official source.
- Signature — Confirm a signature line exists on the final page for submission.
Quick Facts
Downloads
After you file
- 1Keep a copy of the completed IRS Form 1040S1.
- 2Attach Schedule 1 to your main tax return, either Form 1040, 1040-SR, or 1040-NR.
- 3Ensure you enter the total from line 10 (Part I) and line 26 (Part II) onto the corresponding lines of your main Form 1040, 1040-SR, or 1040-NR.
- 4Confirm that the revision date on the form reads 20/25.
Sources
- SRCInstructions p.1 — Schedule 1 attaches to Form 1040, 1040-SR, or 1040-NR.
- SRCInstructions p.1 — For the year 2025, enter amounts reported on Form(s) 1099-K that were included in error or for personal items sold at a loss (Line 1).
- SRCInstructions p.1 — Part I includes Taxable refunds, credits, or offsets of state and local income taxes (Line 1a).
- SRCInstructions p.2 — Part II includes Educator expenses (Line 11) and Health savings account deduction (Line 13).
- SRCInstructions p.2 — Line 26 is the final total of adjustments to income, which must be entered on Form 1040, 1040-SR, or 1040-NR.
- SRCInstructions p.1 — The form's revision date is noted as 20/25 (Line 1).
- SRCNot stated in the official source — verify on the agency site — There is no specific mention of a filing deadline for this form itself, only that it attaches to the main return.
- SRCInstructions p.1 — Line 8 includes various income types such as Gambling (8b), Cancellation of debt (8c), and Stock options (8k).
Common confusion points
What do I put in the box for Form(s) 1099-K?
This is for amounts reported to you on Form(s) 1099-K that were included in error or relate to personal items sold at a loss.
→ Check if the amount fits this description before entering it.
Where do other income types go besides Part I, line 8?
Many specific types of income have dedicated lines (e.g., Gambling on 8b, Stock options on 8k), but some require attaching a schedule (e.g., Rental real estate requires Schedule E).
→ Review the list in Part I to see if your income has its own designated line.
How do I report an adjustment like 'Health savings account deduction'?
This is listed on Part II, line 13, and requires attaching Form 8889.
→ Ensure you attach Form 8889 when reporting this specific deduction.
Do I need to list every single income source?
No; the form provides dedicated lines for many items (lines 1 through 7, and lines 8a through 8z), but an 'Other income' line (8z) allows you to list types and amounts not covered elsewhere.
→ Use a specific line when available; use line 8z only if no other specific line applies.
What is the difference between Part I and Part II?
Part I covers Additional Income, while Part II covers Adjustments to Income (which reduce your gross income).
→ Line 10 summarizes all of Part I's additions, and line 26 summarizes all of Part II's deductions.
If I have multiple adjustments, do they all go on one line?
No; each adjustment has its own line number (e.g., Educator expenses is line 11), although there is a catch-all 'Other adjustments' section (line 24z).
→ List each distinct deduction on its corresponding line unless it falls under the general 'Other adjustments' category.
Workflow map
Related forms and next steps
Before
Current
After
Often used with
⚠ If something goes wrong
- Tax return instructions (For general filing guidance regarding the Paperwork Reduction Act Notice).
Questions about IRS Form 1040S1
What is IRS Form 1040S1 used for?
This form helps you report extra money you earned or deductions that reduce your taxable income beyond what is already listed on your main tax return. It collects details about various types of earnings, from business profits to investment gains and specific adjustments like educator expenses. By completing this, you ensure the IRS has a complete picture of your 2025 financial activity.
Who must file IRS Form 1040S1?
Individuals who file Form 1040, 1040-SR, or 1040-NR must attach Schedule 1 (Form 1040S1) to report their additional income and adjustments.
What information does IRS Form 1040S1 require?
Part I collects your Additional Income, such as taxable refunds or business profit. Part II lists the Adjustments to Income, including health savings account deductions and IRA deductions.
When is IRS Form 1040S1 due?
The form is used for tax filing purposes related to the 2025 tax year; a specific deadline date is not stated on the form itself, but it must accompany your main return.
Where do I file IRS Form 1040S1?
The instructions direct filers to go to www.irs.gov/Form1040 for further guidance regarding where to send the completed Schedule 1 (Form 1040S1).
How do I complete IRS Form 1040S1?
First, fill out the identifying information at the top and enter amounts for specific items in Part I (Additional Income). Next, complete Part II by listing all applicable Adjustments to Income. Finally, total these sections and transfer the final figures onto Form 1040, 1040-SR, or 1040-NR.
What happens if IRS Form 1040S1 is filed incorrectly?
Failure to correctly report income or adjustments on Form 1040S1 can result in an inaccurate calculation of your tax liability, potentially leading to underpayment penalties.
What do I put in the box for Form(s) 1099-K?
This is for amounts reported to you on Form(s) 1099-K that were included in error or relate to personal items sold at a loss. Check if the amount fits this description before entering it.
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