Your Complete Small Business Income Tax Guide

Small Business Tax Forms, Rates, Filing Information

Two business people calculate their business in the office.
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Small businesses calculate their business profit or loss for income taxes, then include this information on their personal tax returns. This small business tax guide will help you determine which forms to use and how to compile information for these forms.

This guide is for small businesses filing their tax returns on Schedule C with their personal returns (Form 1040). It includes sole proprietors and single-member LLC, owners. Here is a separate Complete Guide for corporations and S corporations, and a Guide for Business Taxes for Partnerships. 

Due Dates

Because small businesses file their business tax returns with their personal returns, the due date is the same as the personal income tax return due date: April 15. If the due date falls on a holiday or weekend, the next business day is the due date for that year.

Do I Need a Tax Preparer?

A very simple small business with no cost of goods sold or assets to be depreciated might be able to use a tax software program, but most small businesses need a tax preparer.

Partnership income taxes can be very complicated, and even a simple Schedule C might be more difficult than you think. Before you enlist the help of a CPA, Enrolled Agent, or another qualified tax preparer to prepare your business taxes, use the information in this guide to help you get ready for business taxes.

Types of Small Businesses and Income Tax Forms

A small business that is not a corporation can be one of three major types, with some differences for individual U.S. states:

  • A sole proprietorship is the default business type if no other business type is registered with a state. A sole proprietorship pays income taxes on the owner's personal tax return. Schedule C (Profit or Loss for a Small Business) is used to calculate the business profit, which is included with other income on the individual business owner's Form 1040.
  • A partnership is registered with a state and consists of several partners. The partnership files an information tax return on Form 1065 and individual partners receive a Schedule K-1 showing their share of the partnership's profits or losses. Schedule K-1 income or loss is included along with the partner's other income on his or her Form 1040.

Small Business Income Tax Forms

Here are the forms you will need for each type of small business (these are PDF documents):

Self-Employment Taxes

Small business owners must pay self-employment taxes (Social Security/Medicare taxes). A tax software program or tax preparer can calculate this tax for you. 

Where and How to File Small Business Income Taxes

You can file your tax return by mail or you can e-file the return. The last page of the instructions for Form 1040 lists the addresses to use for mailing your tax return to the IRS. 

Filing an Application for an Extension on Your Taxes

You may apply for an automatic extension of time to file your taxes, including small business taxes. The extension is for six months for non-corporate tax returns, so the due date for the return is October 15 (unless October 15 is a weekend or holiday).

Your extension doesn't include an extension for payment.

You must pay estimated taxes when by the April tax return due date.

Filing an Amended Tax Return

If you make a mistake on your tax return, whether the error is due to your business or to personal taxes, you must file an amended return. The form to amend your tax return depends on your business type.

  • To amend your personal return, including Schedule C, use Form 1040X-Amended Return.
  • To amend a partnership return. get another Form 1065 and check box G(5) on page 1. The IRS says you should attach a statement that identifies the line number of each amended item, the corrected amount or treatment of the item, and an explanation of the reasons for each change.
  • If you filed a partnership return and there is an error on Schedule K-1, or if the change to 1065 causes a change in the information on the K-1, prepare an amended K-1. Check the "Amended K-1" box on the top of the Schedule K-1 to indicate that it has been amended. Then give the amended Schedule K-1 to the partner/member to file.

    Paying Estimated Taxes

    If you don't pay enough taxes during the year, you must pay estimated taxes. Many small business owners must pay estimated taxes because they don't earn a salary, so no taxes are withheld from their income from self-employment. 

    The Qualified Joint Venture: A Special Filing Case

    If you and your spouse are joint owners of a partnership, you may be able to file a qualified joint venture. It means filing two Schedule C forms, for your respective shares of the business. It's complicated, so check with your tax professional to make sure you and your business qualify.