Quick overview

Form 1040 is the IRS’s primary individual income tax return. For first‑time filers it may feel overwhelming, but the process follows a consistent sequence: collect documents, pick the correct filing status, report income, choose deductions or credits, calculate tax, attach schedules when needed, and file (electronically or by mail). In my 15 years advising clients I’ve found that organization and one careful review cut the most common errors.

(For the IRS’s official information, see About Form 1040: https://www.irs.gov/forms-pubs/about-form-1040.)

Step‑by‑step checklist for first‑time filers

  1. Gather essential documents

  • W‑2(s) from employers showing wages and withholding.

  • 1099 forms for non‑employee compensation (1099‑NEC), miscellaneous income (1099‑MISC), interest (1099‑INT), dividends (1099‑DIV), retirement distributions (1099‑R), and broker statements for capital gains or losses.

  • Records of deductible expenses if you plan to itemize: mortgage interest (Form 1098), property tax statements, charitable receipts, medical bills, and unreimbursed business expenses (if eligible).

  • Records for education credits (Form 1098‑T), student loan interest (Form 1098‑E), and childcare (provider’s tax ID and amounts).

  • Social Security numbers (SSNs) or Individual Taxpayer Identification Numbers (ITINs) for yourself, spouse, and dependents.

    In my practice, missing one 1099 has been the biggest source of amended returns. Create a folder (digital or paper) and add documents throughout the year.

  1. Choose the correct filing status
  • Single, Married Filing Jointly, Married Filing Separately, Head of Household, or Qualifying Widow(er). Your filing status affects standard deduction, tax brackets, and eligibility for many credits. Erroneous status selection is a common cause of incorrect refunds.
  1. Complete personal information accurately
  • Full legal names, SSNs/ITINs, and your current mailing address. A typo in an SSN or name can delay refunds or trigger IRS correspondence.
  1. Report all income

  • Wages (Box 1 on W‑2), taxable interest and dividends, retirement distributions, unemployment income, and net self‑employment income (Schedule C).

  • If you received 1099‑NEC or 1099‑K income, treat it as taxable unless you have records proving otherwise.

  • Keep records of estimated tax payments you made during the year.

    Tip from practice: clients sometimes forget taxable portions of scholarships or forgiven debt — when in doubt, check IRS guidance or consult a preparer.

  1. Decide standard vs itemized deduction
  • Most taxpayers take the standard deduction, but itemizing can save more if you have large mortgage interest, state and local taxes (SALT, subject to the $10,000 cap), or unreimbursed medical expenses that exceed the threshold. See IRS Publication and Instructions for amounts that change annually (IRS, Instructions for Form 1040: https://www.irs.gov/pub/irs-pdf/f1040.pdf).
  1. Claim credits that reduce tax dollar‑for‑dollar
  • Common credits include Earned Income Tax Credit (EITC), Child Tax Credit (CTC), the Saver’s Credit, and education credits (American Opportunity and Lifetime Learning). Credits can often deliver larger benefits than deductions for eligible taxpayers.
  1. Attach required schedules and forms

  • Schedule 1: Additional income and adjustments (e.g., educator expenses, student loan interest adjustments).

  • Schedule 2: Additional taxes (e.g., alternative minimum tax).

  • Schedule 3: Nonrefundable credits.

  • Schedule C and Schedule SE for self‑employment income and self‑employment tax.

    For a practical checklist of typical attachments, see our guide on essential attachments and schedules: “Essential Attachments and Schedules You Might Need with Form 1040” (https://finhelp.io/glossary/essential-attachments-and-schedules-you-might-need-with-form-1040).

  1. Calculate tax and withholding
  • Use the tax tables or tax software to compute tax on taxable income, apply withholding and credits, then determine whether you owe or will receive a refund. Electronic tax‑prep systems calculate this automatically and reduce arithmetic errors.
  1. Review and sign
  • Verify Social Security numbers, bank routing/account numbers for direct deposit, and that all income and credits are entered. If you use a paid preparer, confirm the preparer includes their Preparer Tax Identification Number (PTIN).
  1. File and keep copies
    • E‑file with direct deposit is the fastest way to receive a refund and reduces processing errors. The IRS accepts electronic filing for most Form 1040 returns and many states accept e‑file as well. If you mail a paper return, send by certified mail if you want proof of filing.
    • Keep copies of the return and supporting documents for at least three years (IRS recommends keeping records; some circumstances require longer retention). See IRS guidance on how long to keep tax records (IRS, “Records to Keep”).

Common mistakes and how to avoid them

  • Forgetting to report all income: Compare your W‑2s and 1099s against your bank and brokerage statements. The IRS receives copies, so unreported income commonly triggers notices.
  • Incorrect or missing SSNs: Double‑check dependents’ SSNs — an incorrect SSN can disallow credits.
  • Choosing the wrong filing status: Review definitions for Head of Household or Married Filing Separately before selecting.
  • Math errors and transposed numbers: Use e‑file or tax software to avoid calculation mistakes.
  • Missing supporting schedules: Attach Schedule C for business income and Schedule D for capital gains when required — our checklist on common errors and amended returns can help (see “Common Errors That Require Filing Form 1040‑X”: https://finhelp.io/glossary/common-errors-that-require-filing-form-1040-x/).

Real‑world examples (anonymized)

  • Example 1 — Home office deduction: A freelance client I advised tracked direct expenses and a simple square‑footage calculation for a home office. Proper documentation allowed claimed expenses on Schedule C without raising red flags.
  • Example 2 — Claiming EITC: A first‑time filer who qualified for the Earned Income Tax Credit increased her refund substantially; we confirmed eligibility and income limits before claiming to avoid later IRS adjustment.

These examples underline the value of documentation and pre‑filing review.

Filing options, payments and amending returns

  • E‑file vs paper: E‑filing speeds up processing, reduces errors, and supports direct deposit of refunds. Trusted tax software or an authorized e‑file provider can guide you through the process.
  • If you can’t pay: File on time even if you can’t pay the full amount — filing late increases penalties. The IRS offers installment agreements and short‑term payment options (see IRS Online Payment Agreement tools).
  • Amending a return: If you discover an error after filing, use Form 1040‑X to amend. E‑filing for many amended returns is available; check IRS guidance and consider reading our walk‑throughs on amending returns (for example, “Amending Your Return: When and How to File Form 1040‑X”).

Practical tips and pro checklist before you hit “Submit”

  • Use direct deposit and double‑check bank routing and account numbers.
  • Save PDFs of the filed return and all supporting documents in a dedicated folder.
  • Keep receipts and proof for deductions and credits for at least three years; longer for casualty losses or bad debt (seven years).
  • If you’re self‑employed, reconcile receipts and mileage logs before computing self‑employment tax.
  • If uncertain, invest in a short consult with a CPA or enrolled agent — errors can cost more than an hour of professional time.

Where to find authoritative help

For practical, site‑specific help on attachments and common mistakes, see our related guides:

Professional disclaimer

This article provides general information about filing Form 1040 and is not a substitute for personalized tax advice. Tax law and IRS guidance change regularly; consult a licensed tax professional or the IRS for guidance specific to your situation.