How to File Taxes as an S Corporation: A Step-by-Step Guide

Filing taxes as an S Corporation is more involved than filing as a sole proprietor or single-member LLC — but the process is manageable if you know the steps. You'll need to run payroll, pay yourself a reasonable salary, file Form 1120-S, and issue Schedule K-1s to every shareholder by March 15.

An S Corporation is a pass-through entity. The business itself doesn't pay federal income tax. Instead, income, deductions, and credits flow through to shareholders, who report their share on their personal tax returns. That pass-through structure is what makes S Corps attractive — but it comes with real obligations that don't exist for sole proprietors.

The biggest one: if you work in the business, the IRS requires you to pay yourself a reasonable salary as a W-2 employee before taking any distributions. That salary is subject to payroll taxes — Social Security and Medicare — just like any other employee's wages. Skipping this step or setting your salary too low is one of the most common mistakes S Corp owners make, and the IRS looks for it.

Before you can file S Corp taxes, you need a payroll system in place. The IRS requires shareholder-employees to receive reasonable compensation — meaning a salary comparable to what you'd pay someone else to do the same work. There's no fixed dollar amount, but the IRS uses industry data and your business's income to evaluate whether your salary is defensible.

Once you've set your salary, you need to withhold federal income tax, Social Security tax (6.2%), and Medicare tax (1.45%) from each paycheck. The S Corp also pays the employer's matching share of Social Security (6.2%) and Medicare (1.45%) on top of that. At the end of the year, you'll issue yourself a W-2 — the same form any employer issues to employees.

Payroll taxes don't wait until year-end. You need to deposit withheld income taxes and FICA taxes on a regular schedule — either monthly or semi-weekly, depending on your total payroll tax liability. All federal payroll tax deposits go through the Electronic Federal Tax Payment System (EFTPS), which is free to use.

On top of deposits, you'll file Form 941 every quarter to report the wages you paid, the taxes you withheld, and the employer's share of FICA. Form 941 is due by the last day of the month following each quarter — April 30, July 31, October 31, and January 31. You'll also file Form 940 once a year to report federal unemployment (FUTA) tax.

S Corp shareholders who expect to owe $1,000 or more in federal income tax for the year need to make quarterly estimated tax payments. Because S Corp income passes through to your personal return, you're responsible for paying income tax on your share of the business's profits — not just on your W-2 salary.

Estimated payments are due four times a year: April 15, June 15, September 15, and January 15 of the following year. Missing these payments doesn't just mean a bigger bill in April — you can also owe an underpayment penalty. A tax professional can help you figure out the right payment amounts based on your projected income and deductions.

Form 1120-S is the S Corporation's annual income tax return. It reports the business's income, deductions, and credits for the year. The deadline is March 15 for calendar-year S Corps — one month earlier than the April 15 deadline for individual returns. If you need more time, you can file for a six-month extension using Form 7004, which pushes the deadline to September 15.

Along with Form 1120-S, you need to issue a Schedule K-1 to every shareholder by March 15. The K-1 breaks down each shareholder's share of the business's income, deductions, and credits — the numbers they'll use to complete their personal tax returns. If you're the only shareholder, you'll issue one K-1 to yourself. The March 15 deadline matters here: shareholders can't finalize their personal returns until they have their K-1.

Yes, you can file S Corp taxes yourself — but it's more involved than a personal return. You'll need to handle payroll throughout the year, make quarterly deposits and estimated payments, complete Form 1120-S, and issue Schedule K-1s. Most S Corp owners who file on their own use tax software designed for business returns, or they handle the bookkeeping themselves and hire a CPA for the annual filing.

The part that trips people up most often isn't the annual return — it's the payroll. Getting payroll set up correctly from the start, depositing taxes on schedule, and filing Form 941 each quarter takes consistent attention. If you miss a deposit or file Form 941 late, the IRS charges penalties. For many S Corp owners, the annual return is manageable to DIY, but payroll is worth outsourcing.