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Form 1040S1S: 1040 (Schedule 1) (sp)
IRS Form 1040S1S is an attachment to Forms 1040, 1040-SR, or 1040-NR that details additional income and adjustments for taxpayers in 2025. For 2025, the form requires reporting amounts from Form 1099-K included incorrectly.
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IRS Form 1040S1S - 1040 (Schedule 1) (sp)
IRS Form 1040S1S is an attachment to Forms 1040, 1040-SR, or 1040-NR that details additional income and adjustments for taxpayers in 2025. For 2025, the form requires reporting amounts from Form 1099-K included incorrectly.
Risk Radar
Scan points- 1Ensure you correctly report amounts from Form 1099-K listed on Line 2 for 2025.
- 2Failing to list income from Form 1099-K on Line 2 (for 2025).
- 3Not totaling the figures correctly onto Line 10 of the IRS Form 1040S1S.
- 4Omitting required attachments, such as Anexo C for business income.
- 5Incorrectly reporting pension amounts received on Line 2a of Part I.
Plain English
This form helps taxpayers report extra money earned or specific deductions they need to add to their main tax return (Form 1040). It also allows them to list various adjustments that reduce taxable income. By completing this, the taxpayer ensures all sources of 2025 earnings are accounted for correctly.
Submission Date
- Filing date: 2026-01-07 11:10:39
- 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 you need to report additional income or adjustments to your income that must be attached to Form 1040, 1040-SR, or 1040-NR for the 2025 tax year.
- Do not use it when all of your required supplemental income and adjustments fit entirely on the main body of Form 1040.
- Check Schedule C (Form 1040) instead when reporting income or loss from a business.
Form selector
Use this form or another form?
Income/Loss from Business
You must attach it to report income or loss from a business.
✓ Check the required attachment box on Form 1040S1S.
Medical Savings Account Deductions
This form is needed to claim deductions for medical savings accounts (line 13).
✓ Ensure you attach Form 8889 when claiming these costs.
Self-Employment Income/Loss
Use this schedule to report the deductible portion of self-employment tax.
✓ Reference line 15 on Form 1040S1S.
Deadline or filing window
The IRS Form 1040S1S pertains to the 2025 tax year. The instructions direct users to visit www.irs.gov/Form1040SP for specific filing deadlines; no explicit deadline date is listed on this form itself.
Checklist
What you need before filling it out
Total Additional Income (Line 10)
Sum of lines 1 through 9 · Form 1040S1S, Part I & II
Incorrectly Reported 1099-K Amount
Amount reported on the Form 1099-K that was included incorrectly (Form p.1) · Line for SSN reporting section (Form p.1)
Rental Income/Royalties (Line 5)
Total from rental property, royalties, S corps, trusts, etc. · Form 1040S1S, Part I (Form p.1)
SEP/SIMPLE Deductions (Line 16)
Amount related to SEP, SIMPLE plans, and qualified self-employment plans · Form 1040S1S, Part II (Form p.2)
Foreign Income Exclusion (Line 8d)
The specific amount excluded from foreign income reported on Form 2555 · Form 1040S1S, Part I (Form p.1)
Before you submit
- 1Confirm all amounts listed in Part I are totaled correctly into Line 9.
- 2Verify that the total from Line 9 is accurately transferred to Line 10 on Form 1040S1S.
- 3Check that any income or loss reported on Lines 3, 5, 6, or 8 requires an attached schedule (e.g., Schedule C for Line 3).
- 4Ensure the amount of reimbursement returned in excess of 2025 is correctly entered on Line 7.
- 5Verify that if you received a pension from a non-qualified deferred compensation plan, it is recorded on Line 8t.
- 6Confirm that any item listed under Lines 8a through 8z has the appropriate check box marked or amount noted in Line 8z.
- 7If applicable, ensure Form 2106 is attached when reporting certain military/government service expenses (Line 12).
How to file this form
- 1Complete Part I by entering all additional income and adjustments on Lines 1 through 7, and then detailing items on Line 8.
- 2Calculate the total of all other incomes by summing lines 8a through 8z, recording this sum on Line 9.
- 3Total the amounts from Lines 1 through 7 plus Line 9 to find your Total Additional Income, which is recorded on Line 10.
- 4Attach any required supporting schedules (e.g., Schedule C for business income or Schedule E for rental income).
- 5Sign the Form 1040S1S before submitting it with your main tax return.
Known limitations
- 1The amounts listed in Form 1099-K that are *not* reported on this form must be declared elsewhere on the tax return, depending on the nature of the transaction (Instructions p.1).
- 2If a taxpayer refunds an excess payment for 2025, they must mark and note the refunded amount in a specific spot on Form 1040S1S (Instructions p.1).
- 3The form requires separate reporting for certain types of income/adjustments that are listed individually, such as 'Juegos y apuestas' or 'Deuda cancelada' (Instructions p.1).
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 the source directs users to www.irs.gov/Form1040SP for the most recent instructions and information.
What changed or needs a fresh check
- Edition date — confirm the revision reads 20/25.
- Form Number — confirm the form is labeled 1040 (Schedule 1) (sp).
- Mailing address — Not stated in the official source.
- Signature — Sign before sending, as required for filing.
Quick Facts
Downloads
After you file
- 1Keep a copy of the completed IRS Form 1040S1S.
- 2The form is an attachment to Forms 1040, 1040-SR, or 1040-NR (Instructions p.1).
- 3Totaling other income on Line 9 must be done by summing lines 8a through 8z of Form 1040S1S (Instructions p.1).
- 4The final total of 'Otros ingresos' (Line 9) is entered onto Line 8 of the main tax form (Form 1040, 1040-SR, or 1040-NR) (Instructions p.1).
- 5Totaling adjustments on Line 25 must be done by summing lines 11 through 23 of Form 1040S1S (Instructions p.2).
Sources
- SRCForm 1040S1S is an attachment to Forms 1040, 1040-SR or 1040-NR for the 2025 tax year (Instructions p.1).
- SRCFor 2025, taxpayers must report amounts from Form 1099-K that were included incorrectly or resulted in losses from personal property sales (Instructions p.1).
- SRCIf a taxpayer refunds an excess payment for 2025, they mark and note the amount on Form 1040S1S (Instructions p.1).
- SRCOther income types include 'Juegos y apuestas' (8b), 'Deuda cancelada' (8c), and 'Exclusión de ingresos devengados en el extranjero del Formulario 2555' (8d) (Instructions p.1).
- SRCThe total of other income (Line 9) is the sum of lines 8a through 8z (Instructions p.1).
- SRCAdjustments to Income include 'Gastos del educador' (11), 'Deducción por cuentas de ahorros médicos' (13), and 'Gastos de mudanza para miembros de las Fuerzas Armadas' (14) (Instructions p.2).
Common confusion points
What do I report for the amounts from my 1099-K?
The form requires reporting incorrect amounts; other amounts must be declared elsewhere on your return (Instructions p.1).
→ Check if you are only listing items that were included incorrectly.
Where does 'Otros ingresos' total go?
The sum of lines 8a through 8z is the total for Line 9, which then carries over to Line 8 of the main Form 1040 (Instructions p.1).
→ Ensure you are summing all listed income types on Line 8.
What do 'Ajustes al Ingreso' go into?
The final sum of adjustments (Line 26) is entered onto Line 10 of the main tax form (Form 1040, 1040-SR, or 1040-NR) (Instructions p.2).
→ Confirm you are summing lines 11 through 23 for this total.
Do I need to list every single income type?
No; the form allows for specific line items (e.g., 'Juegos y apuestas'), but Line 8z covers any other income not listed, requiring a description and amount (Instructions p.1).
→ Verify that you have accounted for all income sources from your documents.
What if I only claim storage costs?
If claiming only storage charges under the business expense deduction, mark the relevant box on Form 1040S1S (Instructions p.2).
→ Look specifically at Line 14 regarding 'Gastos de mudanza para miembros de las Fuerzas Armadas'.
What is the difference between income and adjustments?
Income is reported in Part I (Lines 8a-9); Adjustments are reported in Part II (Lines 11-26) (Instructions p.1, p.2).
→ Check which section of the form the specific item falls under.
Workflow map
Related forms and next steps
Before
Current
After
Often used with
⚠ If something goes wrong
- Form 2555 (Needed for reporting foreign earned income exclusion, Line 8d) (Instructions p.1)
- Form 2106 (Used to support certain business expenses/deductions, Line 12) (Instructions p.2)
- Form 8889 (Used for medical savings account deductions and other adjustments, Lines 13 & 15) (Instructions p.2)
Questions about IRS Form 1040S1S
What is IRS Form 1040S1S used for?
This form helps taxpayers report extra money earned or specific deductions they need to add to their main tax return (Form 1040). It also allows them to list various adjustments that reduce taxable income. By completing this, the taxpayer ensures all sources of 2025 earnings are accounted for correctly.
Who must file IRS Form 1040S1S?
Taxpayers must file IRS Form 1040S1S if they have additional income or adjustments to report on their Form 1040, 1040-SR, or 1040-NR. The form is used by anyone whose main return requires this attachment.
What information does IRS Form 1040S1S require?
Part I collects details like taxable amounts from state/local tax refunds and pensions received. Part II captures various adjustments to income, such as educator expenses and retirement plan contributions.
When is IRS Form 1040S1S due?
The filing deadline timing is not explicitly stated for the entire form in a single section, but the information relates to the 2025 tax year.
Where do I file IRS Form 1040S1S?
The instructions direct users to visit www.irs.gov/Form1040SP for specific guidance on where to send the completed IRS Form 1040S1S.
How do I complete IRS Form 1040S1S?
First, complete Part I by listing additional income items (like pension or business profit). Next, fill out Part II with income adjustments (such as medical savings deduction). Finally, sum these totals and transfer them to lines 10 on this form and line 8 of the main Form 1040, 1040-SR, or 1040-NR.
What happens if IRS Form 1040S1S is filed incorrectly?
If the amounts reported are incorrect, the tax liability calculation will be wrong, potentially leading to underpayment or overpayment of taxes owed to the Department of the Treasury.
What do I report for the amounts from my 1099-K?
The form requires reporting incorrect amounts; other amounts must be declared elsewhere on your return (Instructions p.1). Check if you are only listing items that were included incorrectly.
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