Federal and state tax, decoded.
How your entity is actually taxed, which deadlines bite, and the elections that change everything. Written by the specialists who prepare these returns, verified against IRS instructions, and free.
Start from the question you actually have.
Four shelves, each answering one kind of tax question. Every guide is complete on its own and links to the others.
Most-read right now.
Default pass-through, the corporate option, and where the S-corp fits.
Read → The electionThe S-corp electionWhat it changes, who it helps, and the payroll duty it creates.
Read → Deadlines2026 tax deadlinesEvery federal date for a small business this year, in one calendar.
Read → Pay as you goQuarterly estimated taxesWhy the IRS wants four payments, and how owners size them.
Read →Five dates carry most of the weight.
Exact days shift for weekends and holidays, and states add their own. These are the federal anchors.
Final estimated payment for last year
The fourth quarterly payment closes out the prior tax year. How the quarterly system works.
S corporations and partnerships file
Form 1120-S and Form 1065 are due, and K-1s go out to owners. The 1120-S walkthrough.
Individuals and C corporations file, Q1 begins
Schedule C filers and C corporations file, and the first estimated payment of the new year is due the same day. Schedule C, explained.
Quarters two and three
Two more estimated payments as profit comes in. Size them with the calculator rather than guessing.
Sales tax on its own cycle
Where you have nexus, sales tax filings run monthly or quarterly on the state's schedule, separate from income tax. Where nexus comes from.
Business tax has exactly two models. Learn both here.
Every entity, election, and form on this page is a variation on two ideas. Understand them and nothing on a tax form will surprise you again.
The company itself pays no federal income tax. Profit passes through to the owners' personal returns the year it is earned, sold or not, spent or not. On top of income tax, active owners owe self-employment tax of 15.3 percent toward Social Security and Medicare. This is the default for LLCs, partnerships, and S corporations.
Default LLC · partnership · S-corp · Schedule C, 1065, 1120-SThe company is its own taxpayer and pays the flat 21 percent federal corporate rate on profit. Owners are taxed a second time when profit reaches them as dividends, which is the famous double taxation. In exchange, profit left in the company is taxed once at 21 percent, which is why growth companies that reinvest everything often choose it.
C corporation · Form 1120 · dividends taxed at the ownerEverything else is an election that moves you between the models or softens their edges. The S-corp election keeps pass-through treatment but splits owner pay into salary and distributions, and only the salary carries the 15.3 percent, which is the entire savings. The check-the-box rules let one LLC choose any of the four treatments without changing its legal form.
| Your setup | Who pays income tax | 15.3% SE / payroll tax | Federal form | When it wins |
|---|---|---|---|---|
| LLC, one member | You, on Schedule C | On all profit | Schedule C | Simplicity, early profits |
| LLC, multi-member | Each member, via K-1 | On active members' shares | Form 1065 | Partners with flexible splits |
| S corporation | Owners, via K-1 | Salary only, not distributions | Form 1120-S | Steady profit well above a fair salary |
| C corporation | The company at 21%, then dividends | Owner salaries only | Form 1120 | Reinvested profit, venture investors |
The tax library, answered.
Where should a brand-new owner start?
With how LLCs are taxed, even if you formed a corporation, because it explains the pass-through system everything else builds on. Then read the deadlines calendar so nothing surprises you, and the quarterly guide if the business is already earning.
Is the S-corp election worth it for me?
It depends on profit, payroll, and state, which is why the election guide walks through the real tradeoffs, including the payroll obligation it creates from day one. The savings calculator gives you a first estimate with your own numbers, and payroll setup shows what changes after you elect.
What is the difference between income tax and self-employment tax?
Income tax is on profit; self-employment tax funds Social Security and Medicare and applies to pass-through owners on top of income tax. The SE tax guide explains the mechanics, and the calculator shows the number for your profit level.
Do I owe sales tax in states where I only ship orders?
Possibly, and this catches e-commerce owners constantly. Physical presence is no longer the only trigger: enough sales into a state can create nexus on its own. The nexus guide covers the thresholds, and registration shows what to do once you cross one.
Which federal form does my company actually file?
Single-member LLCs report on Schedule C, multi-member LLCs file Form 1065, S corporations file Form 1120-S, and foreign-owned single-member LLCs add Form 5472. Each walkthrough covers what the form asks and the mistakes that trigger letters.
Do these guides replace a CPA?
No, and they are honest about where the line is. They give you the working knowledge to make routine decisions and to have a productive conversation with a professional about the rest. When you want the return handled end to end, tax preparation is the service, and what it costs lives on pricing.
Understand it. Then hand it over.
Read enough to decide. File none of it yourself.
The returns, the elections, and the quarterly math can all be prepared and reviewed by specialists, with the guides as your window into what they are doing and why.
Government deadlines above are verified against IRS instructions. Service costs live in one place: pricing.