Playing now

Playing now

Know your tax dates & IRS forms with our calendar

Back to search results

Man filling out paperwork

Update: On March 17, 2021 The IRS and Treasury Department announced the April 15 tax-filing deadline has been postponed to May 17.  We are in the process of updating our 2021 calendar to reflect this change.  

Let’s be honest: Getting your business tax right can be difficult.

Our 2021 business tax calendar can help. It lists the following, that most businesses will likely to need to know:

  • Dates taxes should be filed
  • IRS forms businesses must file

The calendar includes links to the IRS website for each filing requirement/form where you can learn more about what’s required and what you need to do.

In this article we take a look at the basics of what tax forms a business is likely to require. Hey, it might not be very interesting—but if you’re running a business it’s essential knowledge!

What’s listed below does not constitute legal or professional advice. As always, if you’re in any doubt about what tax you or your business should pay, or what form is required, consult a CPA or the IRS itself.

The basics of IRS tax requirements for business

There are essentially three kind of federal taxes for businesses: income, employment, and excise.

All businesses must file income tax returns, regardless of whether that’s a sole proprietorship, partnerships, corporations, S corporations, and Limited Liability Company (LLC). However, partnerships are slightly different because they file an information return instead and the partners file the taxes as individuals.

Businesses might need to file employment taxes such as social security and Medicare, federal income tax withholding, and federal unemployment tax (FUTA). An additional set of forms are required.

If your business manufactures or sells certain products, uses various kinds of equipment facilities or products, receive payments for certain services, or is just a certain kind of business then it might have to file excise tax too. Federal excise taxes are reported using Form 720 (Quarterly Federal Excise Tax Return). There may be environmental taxes, communication and air transportation taxes, fuel taxes, manufacturers’ taxes on the sale or use of a variety of different articles, and taxes on the first retail sale of heavy trucks, trailers, and tractors. All have their own IRS forms.

IRS forms required for business

So, which kinds of federal taxes and forms are likely to be required for the various types of business, corporations or partnerships in the USA? Here’s a non-exhaustive list, excluding excise taxes, which will depend on the nature of your business, and any information returns processing that might be required.

IRS forms required by a sole proprietor

If you own and run an unincorporated business then you’re a sole proprietor (unless you’re the sole member of a domestic LLC and elect to treat the LLC as a corporation, as discussed below).

The forms you may need are as follows:

  • Income tax: Form 1040 (U.S. Individual Income Tax Return) and Schedule C (Form 1040, Profit or Loss from Business), or Schedule C-EZ (Form 1040, Net Profit from Business).
  • Estimated tax: 1040-ES (Estimated Tax for Individuals).
  • Social security and Medicare taxes and income tax withholding: Form 941 (Employer’s Quarterly Federal Tax Return), Form 943 (Employer’s Annual Federal Tax Return for Agricultural Employees), Form 944 (Employer’s Annual Federal Tax Return), W-2 (Wage and Tax Statement), and W-3 (Transmittal of Wage and Tax Statements).
  • Self-employment tax: Schedule SE (Form 1040, Self-Employment Tax).
  • FUTA: Form 940 (Employer’s Annual Federal Unemployment (FUTA) Tax Return).

IRS forms required by corporations

If your business is classed as a corporation then it’s probably be a C corporation, although it might be an S corporation. The primary difference is that a C corporation pays tax based on its income, while an S corporation is a pass-through/flow-through business that passes both income and losses through to shareholders for them to handle taxes individually.

The forms a C corporation might require are as follows:

  • Income tax: Form 1120 (U.S. Corporation Income Tax Return).
  • Estimated tax: Form 1120-W (Estimated Tax for Corporations).
  • Employment taxes: Form 941 (Employer’s Quarterly Federal Tax Return), or Form 943 (Employer’s Annual Federal Tax Return for Agricultural Employees), and Form 940 (Employer’s Annual Federal Unemployment (FUTA) Tax Return).

The forms an S corporation might need to file are as follows:

  • Income tax: Form 1120S (U.S. Income Tax Return for an S Corporation), and Form 1120S Sch. K-1 (Shareholder’s Share of Income, Deductions, Credits, etc.)
  • Estimated tax: Form 1120-W (Estimated Tax for Corporations)
  • Employment taxes: Form 941 (Employer’s Quarterly Federal Tax Return), Form 943 (Employer’s Annual Federal Tax Return for Agricultural Employees), and Form 940 (Employer’s Annual Federal Unemployment (FUTA) Tax Return).

The forms S corporation shareholders might require are:

  • Income tax: Form 1040 (U.S. Individual Income Tax Return), Schedule E (Supplemental Income and Loss), plus other forms referenced on the shareholder’s Schedule K-1
  • Estimated tax: Form 1040-ES (Estimated Tax for Individuals).

IRS forms required by partnerships

Partnerships comprise two or more people who all work on the business, contributing their labor, skills, money or property. As a result, they get a share in the profits and losses of the business.

Partnerships file information returns because they don’t pay income tax. Instead, profit and losses are passed through to the partners, and the partners then file their own tax returns.

The partnership might need to file the following:

  • Annual return of income: Form 1065 (U.S. Return of Partnership Income).
  • Employment taxes: Form 941 (Employer’s Quarterly Federal Tax Return), Form 943 (Employer’s Annual Federal Tax Return for Agricultural Employees), and Form 940 (Employer’s Annual Federal Unemployment (FUTA) Tax Return).

The individual partners might need to file the following:

  • Income tax: Form 1040 (U.S. Individual Income Tax Return), and Schedule E (Form 1040, Supplemental Income and Loss).
  • Self-employment tax: Form 1040 (U.S. Individual Income Tax Return), and Schedule SE (Form 1040, Self-Employment Tax).
  • Estimated tax: Form 1040-ES (Estimated Tax for Individuals).

IRS forms required by LLCs

A Limited Liability Company, or LLC, is a kind of business that varies depending on the state its based on because each state might have differing regulations. Its owners are called members.

However, from a federal tax perspective the IRS typically considers an LLC to be either a corporation or partnership. The latter applies for domestic LLCs with at least two members unless the LLC files Form 8832 (Entity Classification Election) and thereby elects that the LLC should be treated as a corporation.

A LLC with just one member is considered to be a “disregarded entity”, which is to say it’s considered to be part of the owner’s tax return—unless, as above, Form 8832 is filed so the LLC is treated as a corporation. However, a one-member LLC is still a separate entity for the purposes of employment and certain excise taxes.

Therefore, the IRS forms needed by an LLC will be those of a partnership, corporation or sole trader, as listed above.

Advice for completing IRS tax forms

It isn’t difficult to get hold of the required tax forms, or to learn about how they should be completed.

The IRS lists all forms and publications it has available, and finding the one you require is as simple as using the search box. All are available as PDF documents, which means to read and complete them electronically you’ll need PDF reader software such as Adobe Acrobat Reader. Ensure you get the correct form for the year for which you’re filing, because forms are often updated.

The IRS makes available a number of publications and instruction documents to help with the completion of forms, and these can be read online using any web browser. Note that some publications are updated each year. The year is typically indicated in the title, so be sure to read the correct publication for the current tax year.

The IRS also makes available a number of eBook publications that provide guidance on forms and taxes, which can be read on your mobile device.


Editor’s note: The information contained herein is for general guidance purposes only. All dates have been checked against official sources, but you should consult the IRS, a CPA, or a dedicated tax specialist for more information on what each entails. 

2021 Business Tax Calendar

Don't miss important deadlines - and ensure you use the correct forms with this calendar showing key dates in the general tax, employer's tax, and excise tax year for 2021.

Download Calendar

Subscribe to our Sage Advice Newsletter

Get our latest business advice delivered directly to your inbox.

Ask the author a question or share your advice

When you leave a comment on this article, please note that if approved, it will be publicly available and visible at the bottom of the article on this blog. While your email address will not be publicly available, we will collect, store and use it, along with any other personal data you provide as part of your comment, to respond to your queries offline, provide you with customer support and send you information about our products and services as requested.  For more information on how Sage uses and looks after your personal data and the data protection rights you have, please read our Privacy Policy.

Sage Advice Logo

Comments (2)

  • On the Sage Advice Tax Calendar, there doesn’t appear to be an entry on March 15 for Partnerships. It actually looks like the S-Corp item got combined with the Partnership information rather than keeping them separate. Of course, they are very similar, but the K-1 (1065) does NOT get filed with the 1120S, and there is no mention of the K-1 (1120S) or the 1065.


      Hi Amy, thank you for pointing that out. We will make that revision to the calendar.