Understanding your tax return
A plain-English walk-through of Form 1040 and the three schedules we attach most often. Find your line number and see what it means.
Form 1040 — U.S. Individual Income Tax Return
The main form. Every other schedule eventually feeds a number back into one of these lines.
Income — what came in
Lines 1–9Wages
Total wages from Box 1 of all your W-2s — your pay before pre-tax deductions like your 401(k) or health insurance.
Taxable interest
Interest earned on savings, CDs, or bonds, reported to you on Form 1099-INT.
Ordinary dividends
Dividends paid by stocks or funds you own, reported on Form 1099-DIV.
IRA distributions (taxable amount)
Money you withdrew from a traditional IRA, from Form 1099-R.
Pensions & annuities (taxable amount)
The taxable part of pension or annuity payments you received, from Form 1099-R.
Social Security benefits (taxable amount)
Up to 85% of your Social Security benefits can be taxable, depending on your other income. Reported to you on Form SSA-1099.
Capital gain or loss
Profit or loss from selling stocks, funds, or other investments, calculated on Schedule D.
Additional income
A catch-all for income types like self-employment or rental income. The breakdown lives on Schedule 1.
From Schedule 1, line 10Total income
Everything above, added together — the full picture before any adjustments.
Adjustments & deductions — what reduces your taxable income
Lines 10–15Adjustments to income
Specific expenses the IRS lets you subtract before your deduction, like IRA contributions or student loan interest.
From Schedule 1, line 26Adjusted Gross Income (AGI)
Total income minus adjustments. AGI is the number most other tax calculations — deduction phase-outs, credit eligibility — are based on.
Standard or itemized deduction
A flat amount everyone gets to subtract (the standard deduction), or your actual deductible expenses from Schedule A if that total is larger (itemizing).
Qualified Business Income (QBI) deduction
If you have self-employment, partnership, S-corp, or rental income, you may deduct up to 20% of it.
Additional deductions (new for 2025)
Newer deductions created by recent tax law — for qualifying tip income, overtime pay, auto loan interest, or a senior deduction — calculated on Schedule 1-A.
Taxable income
Your income after every deduction. This is the number the tax tables actually apply to.
Tax & credits — what you owe, before it's lowered
Lines 16–24Tax
The tax owed on your taxable income, based on the tax brackets for your filing status.
Amount from Schedule 2
Extra taxes like the Alternative Minimum Tax, added in here.
From Schedule 2, line 3Child Tax Credit / Credit for Other Dependents
A credit for each qualifying child or dependent, which directly reduces tax owed (more valuable than a deduction).
Amount from Schedule 3
Other credits you qualify for — education, child care, foreign taxes — rolled in from Schedule 3.
From Schedule 3, line 8Tax after credits
Your tax liability once every credit has been applied.
Other taxes
Things like self-employment tax get added back in here.
From Schedule 2, line 21Total tax
The bottom-line tax for the year — what you actually owe before counting what you already paid in.
Payments, refund & amount due
Lines 25–38Federal income tax withheld
Taxes already taken out of your pay or 1099 income during the year — from Box 2 of your W-2s and any 1099 withholding.
Estimated tax payments
Quarterly payments you sent the IRS directly during the year, plus any overpayment applied from last year's return.
Earned Income Credit (EIC)
A refundable credit for working taxpayers with lower to moderate income, especially with children.
Additional Child Tax Credit
The refundable part of the Child Tax Credit — the part you can still get back even if your tax bill is already at zero.
Total payments
Everything you paid in — withholding, estimates, and refundable credits — added together.
Overpayment
If your total payments (Line 33) are more than your total tax (Line 24), this is the overpayment amount — the start of your refund.
Refund
The amount being refunded to you, by direct deposit or check.
Amount you owe
If your total tax (Line 24) is more than what you paid in (Line 33), this is the balance due with your return.
Estimated tax penalty
A small penalty that can apply if you didn't pay enough tax throughout the year, rather than at filing time.
A few terms worth knowing
- AGI
- Adjusted Gross Income — total income minus adjustments. Used to determine eligibility for many deductions and credits.
- Taxable income
- AGI minus your standard or itemized deduction. The amount tax is actually calculated on.
- Deduction vs. credit
- A deduction lowers the income you're taxed on. A credit lowers the tax itself, dollar for dollar — generally worth more.
- Refundable vs. nonrefundable
- A refundable credit can give you money back even past zero tax owed. A nonrefundable credit can only reduce your tax to zero.
Schedule 1 — Additional Income and Adjustments to Income
Attached when you have income or deductions that don't fit directly on Form 1040 — these are the ones we see most often.
Part I — Additional income
Taxable state & local tax refunds
A refund from last year's state return is only taxable if you itemized deductions last year and deducted those state taxes — most clients who take the standard deduction don't owe tax on this.
Business income or loss
Net profit or loss from a sole proprietorship or self-employment, calculated on Schedule C.
Rental, royalty, partnership & S-corp income
Income or loss from rental property, royalties, or a share of a partnership/S-corporation, detailed on Schedule E.
Unemployment compensation
Unemployment benefits you received, reported on Form 1099-G. These are taxable income.
Total additional income
All of Part I added together.
Flows to Form 1040, line 8Part II — Adjustments to income
Educator expenses
K-12 educators can deduct up to $300 of classroom supplies bought with their own money, no itemizing required.
Health Savings Account (HSA) deduction
Contributions you made to an HSA outside of payroll, reported on Form 8889.
Deductible part of self-employment tax
If you're self-employed, you get to deduct half of the self-employment tax you pay — mirroring what an employer would normally cover.
Self-employed retirement plan contributions
Contributions to a SEP, SIMPLE, or other retirement plan set up for self-employment income.
Self-employed health insurance
Health insurance premiums paid for yourself and family, if you're self-employed and not covered by an employer plan.
IRA deduction
Contributions to a traditional IRA that reduce your taxable income, subject to income limits.
Student loan interest
Up to $2,500 of interest paid on qualified student loans, reported to you on Form 1098-E.
Total adjustments
All of Part II added together.
Flows to Form 1040, line 10Schedule 2 — Additional Taxes
Attached when you owe a type of tax beyond the regular income tax calculation — most commonly self-employment tax.
Part I — Tax
Alternative Minimum Tax (AMT)
A parallel tax calculation designed to make sure high-income filers with lots of deductions still pay a minimum amount of tax, computed on Form 6251.
Total — Part I
Added into your tax before credits.
Flows to Form 1040, line 17Part II — Other taxes
Self-employment tax
Social Security and Medicare tax on self-employment income — the equivalent of what's normally split between an employee and employer, calculated on Schedule SE.
Additional tax on IRAs or retirement accounts
Typically the 10% penalty for withdrawing retirement funds before age 59½, unless an exception applies. Details on Form 5329.
Household employment taxes
Social Security, Medicare, and unemployment tax owed if you paid a household employee, such as a nanny or caregiver, calculated on Schedule H.
Additional Medicare Tax
An extra 0.9% Medicare tax on wages or self-employment income above a threshold tied to your filing status.
Net Investment Income Tax (NIIT)
An extra 3.8% tax on investment income — interest, dividends, capital gains, rental income — for higher-income filers.
Total other taxes
All of Part II added together.
Flows to Form 1040, line 23Schedule 3 — Additional Credits and Payments
Attached when you qualify for credits that don't fit directly on Form 1040, or made certain other payments.
Part I — Nonrefundable credits
Foreign tax credit
A credit for income tax you paid to another country — commonly from foreign holdings inside a brokerage account, shown on your 1099.
Child & dependent care credit
A credit for a portion of what you paid for child care (or care for another dependent) so you could work, calculated on Form 2441.
Education credits
The American Opportunity or Lifetime Learning Credit, for tuition and related expenses, from Form 8863.
Retirement savings contribution credit
Also called the "Saver's Credit" — a credit for contributing to a retirement account, for low- to moderate-income filers.
Residential energy credits
Credits for qualifying home solar, energy storage, or energy-efficient improvements like windows, doors, and insulation.
Total nonrefundable credits
All of Part I added together.
Flows to Form 1040, line 20Part II — Other payments & refundable credits
Net premium tax credit
A reconciliation of health insurance subsidies received through the Marketplace against what you actually qualified for, from Form 8962.
Excess Social Security withheld
If you worked for more than one employer and too much Social Security tax was withheld in total, the excess is credited back here.
Total other payments & refundable credits
All of Part II added together.
Flows to Form 1040, line 31