Income tax & brackets
A 1040 tax calculator that sends you the return, not the question
A 1040 tax calculator for tax preparers and CPA firms: clients estimate their 2026 federal income tax from income, adjustments, deductions and credits, and the ones who want it filed properly send you the numbers.
Included on every plan, even the free Practitioner plan. No card needed.
How do you estimate federal income tax for 2026?
Start with gross income, subtract above-the-line adjustments to get AGI, then subtract the larger of the standard deduction or itemized deductions to get taxable income. Apply the 2026 brackets for the filing status (2026 brackets and standard deductions (Rev. Proc. 2025-32)2026 · IRS Rev. Proc. 2025-32), then subtract credits. The result is federal income tax before payroll and state taxes.
February, when the W-2s and 1099s are in
By mid-February most clients have their forms and a nagging question: refund or balance due? Some are deciding whether to file early, some whether they can still afford the do-it-yourself route, and some are reacting to a life change (a marriage, a new job, a side business) that makes last year's return a poor guide. They want a number before they decide who prepares the return.
What the client types into a search box
“how much federal tax will I owe this year”
How a client works through it
Choose a filing status
Single, married filing jointly, married filing separately or head of household. The brackets and standard deduction follow from it.
Enter income and adjustments
Gross income, then pre-tax adjustments such as retirement contributions or HSA deposits, which lower AGI.
Add deductions and credits
Itemized deductions are compared with the standard deduction automatically; credits reduce the tax dollar for dollar.
Read the estimate and send it
Federal tax, effective and marginal rates and after-tax income appear at once, and the client can forward them to your firm.
What lands in your inbox
When a client asks your firm to review the result, the request arrives as a contact record with their inputs and results attached, by email and, on paid plans, by webhook to your CRM.
Received
Gross income and filing status show the likely engagement size. Itemized deductions near the standard deduction suggest a client who needs help choosing. Large adjustments point to self-employment or retirement contributions, and credits entered without detail usually mean the client is unsure whether they qualify, which is a preparer's question.
What do the federal tax, effective rate and marginal rate mean?
Federal Tax is the estimated income tax for the year after credits. Effective Tax Rate divides that tax by gross income, which is the number clients compare with friends and news stories. Marginal Tax Rate is the bracket the last dollar falls in, the number that matters for decisions such as a bonus, a deduction or a Roth conversion.
Taxable Income shows the result after deductions, which helps clients see why their tax is lower than their bracket suggests. After-Tax Income is gross income minus the estimated federal tax only; payroll and state taxes still come out of it, which the client should be reminded of.
Results shown: Federal Tax · Taxable Income · Effective Tax Rate · Marginal Tax Rate · After-Tax Income.
Why a deduction saves less than clients expect
A client in the 22% bracket asks whether a $1,000 deduction 'saves $1,000'. It reduces taxable income by $1,000, so it saves $1,000 × 22% = $220. A $1,000 nonrefundable credit, by contrast, cuts the tax itself by $1,000 as long as there is at least that much tax to offset. The calculator shows both effects side by side when the client changes the inputs.
How do tax firms use a 1040 estimate on their website?
As the front door for the season. A prospect who runs the estimate and sees itemized deductions close to the standard deduction, or credits they are not sure they qualify for, has a concrete reason to ask a preparer. The request arrives with their filing status, income and deductions already entered, so the first call can be about price and documents rather than discovery.
Existing clients use it differently: to sanity-check a refund before their appointment or to model a mid-year change. Firms with a client portal often link it there with lead capture off, and keep a public version with lead capture on for search traffic.
Follow-ups this request opens
- Quote a return preparation fee based on the complexity the inputs show
- Run a full projection including state tax and payroll taxes
- Review whether itemizing beats the standard deduction for this household
- Plan estimated payments if the result shows a balance due
What this calculator leaves out
- Federal income tax only: no state or local income tax, and no Social Security or Medicare tax.
- Long-term capital gains and qualified dividends are taxed at ordinary rates here; preferential rates are not modeled.
- No AMT, no additional standard deduction for age 65+, and no credit phase-outs.
- Credits are entered as a total; eligibility for each credit is not checked.
Platform disclaimer shown under the calculator: Estimates only. Uses 2026 federal tax brackets and standard deductions (IRS Rev. Proc. 2025-32); it does not include state tax, payroll (FICA) tax, capital-gains rates, the additional deductions for age 65+, the many credits/phase-outs, or AMT. Not tax advice — consult a tax professional.
Compliance note for firms
A client-run estimate is not a return and not written advice, but a preparer who replies with commentary is giving advice. Circular 230 §10.37 expects reasonable assumptions and attention to the relevant facts, such as capital gains or AMT that this calculator omits. Keep the not-advice line under the results, and when you reply to a request, say what the estimate left out before you rely on it.
Not legal advice. See our disclaimer and the guide to compliance for client calculators.
2026 figures this page relies on
| Figure | Value | Tax year | Source |
|---|---|---|---|
| Federal income tax brackets and standard deduction | 2026 brackets and standard deductions (Rev. Proc. 2025-32) | 2026 | IRS Rev. Proc. 2025-32, as amended by the 2025 tax law |
| SALT deduction cap used by the 1040 calculator | $40,400 | 2026 | Federal law (2025 tax law), as applied in the calculator |
The same values drive the calculator. Full list on the 2026 figures page.
Terms your client sees in the calculator
These definitions appear in the calculator's collapsible Definitions block, so clients don't have to call to ask what a label means.
- Taxable income
- The income your federal tax is actually calculated on: adjusted gross income minus the larger of the standard deduction or your itemized deductions. It is usually well below gross income. The tax brackets are applied to this number, and credits are subtracted from the resulting tax afterward.
- Filing status
- The category you file under — single, married filing jointly, married filing separately, or head of household — which sets both your tax brackets and your standard deduction. A qualifying surviving spouse uses the married-filing-jointly figures. Status is generally based on your situation on the last day of the year.
- Adjusted gross income (AGI)
- Gross income minus above-the-line adjustments such as traditional 401(k) or IRA contributions and HSA contributions. AGI is the starting point for deductions and is also used to test eligibility for many credits and deductions. In this calculator, AGI equals gross income minus the adjustments you enter.
- Above-the-line adjustments
- Amounts subtracted from gross income to reach AGI, available whether or not you itemize — for example traditional IRA, pre-tax 401(k) and HSA contributions, or student loan interest. Pre-tax payroll contributions are often already excluded from the wages on your W-2, so avoid subtracting them twice.
- Standard deduction
- A flat amount, set by filing status and adjusted yearly for inflation, that you may subtract from AGI instead of itemizing. This calculator uses the 2026 amounts from IRS Rev. Proc. 2025-32 and applies whichever is larger, the standard deduction or your itemized total. It does not add the extra amount for age 65+.
- Itemized deductions
- Specific expenses listed on Schedule A — mortgage interest, state and local taxes, charitable gifts and certain others — used instead of the standard deduction when their total is larger. State and local taxes are capped; this calculator’s 2026 figure for that SALT cap is $40,400 (federal law, 2026).
In our glossary: Taxable income · Adjusted gross income · Effective tax rate · Marginal tax rate · Standard deduction
1040 Federal Income Tax calculator: questions from firms and clients
Which tax year does the 1040 calculator use?
Tax year 2026, with brackets and standard deductions from IRS Rev. Proc. 2025-32 as amended by the 2025 tax law. We re-verify the figures each January; the source list is on the 2026 figures page.
Does it include state income tax?
No. It estimates federal income tax only. Most firms mention their state return service in the button text or in the reply to the request, which is often the reason a client chooses a preparer over software.
Will it tell a client whether they get a refund?
Not directly. It estimates total federal tax for the year. Comparing that figure with federal withholding on the client's W-2s gives a rough refund or balance due. Many firms add that tip to the calculator's subtitle.
Does it handle capital gains and qualified dividends?
No. Capital gains are not taxed at their preferential rates in this estimate, so clients with significant investment income should treat the result as a ceiling and ask the firm for a projection.
Can we change the default income or filing status?
Yes. Defaults, labels and help text are editable per calculator. A firm that mostly serves married couples might default to married filing jointly.
How is this different from the marginal tax rate calculator?
The 1040 calculator estimates the whole year's tax from income, deductions and credits. The marginal tax rate calculator starts from taxable income and focuses on the rate applied to the next dollar.
Can clients use it before they have their forms?
Yes, with estimates. That is how it is most useful in the fourth quarter, when a client can still change the outcome with a retirement contribution or a charitable gift.
Does the SALT cap apply?
Yes. Itemized state and local taxes are capped at $40,4002026 · Federal law in the calculator's 2026 assumptions.
Which plan includes this calculator?
Every plan, including the free Practitioner plan, which runs up to 5 calculators at once alongside the other tax tools. Firm (up to 50) and Network (no cap) add webhooks and white-label. See pricing.
No question matches that filter. Clear it to see them all, search the whole site, or ask us directly; we reply within one business day.
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Answer the February question before the client calls
Embed the 1040 Federal Income Tax calculator on your firm's site in an afternoon and receive requests with the numbers already filled in.
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