Small Business Income Tax Preparation

Tax Return Due Dates for 2018 Business Taxes

Including Due Dates for Extended Business Tax Returns

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Here are the dates you need to remember for filing business taxes, including federal income taxes and extension application deadlines. Details for each business type are included.

2018 Tax Return Due Dates for Business Types 

Sole Proprietorship and Single-member LLC tax returns on (with the owner's personal tax return: April 15, 2019

Partnership returns  on with for each partner: March 15, 2019  

Multiple-member LLC returns on Form 1065 with Schedule K-1 for each member is: March 15, 2019

S corporation returns on Form : March 15, 2019

C corporation returns on : for December 31 year-end corporations, the deadline is April 15, 2019. Corporations must file by the 15th day of the 4th month after the end of its tax year. But corporations with a fiscal year ending June 30 must file by the 15th day of the 3rd month after the end of its tax year. 

Extension Deadlines for 2018 Business Tax Returns

Deadlines for extended business tax returns:

  • Schedule C for sole proprietors and single-member LLC's: extension until October 15, 2019 (no change) filed with the owner's personal tax return
  • Partnership and multiple-member LLC filing as partnership extension deadline is September 16, 2019 (no change, but the date is different because Sept. 15 is a Sunday)
  • S corporation extension deadline is September 16, 2019 (no change)
  • Corporation extension deadline is October 15, 2019 (automatic extension allowed)

Changes: New Tax Return Due Dates for Partnership and C Corporation Returns

Partnership Tax Returns: Effective with the 2016 tax year, partnership tax returns, filed on Form 1065, must be filed by the 15th day of the third month after the tax year end date. For most partnership returns, that's March 15. (The previous due date was April 15). The earlier deadline gives partners a chance to receive Schedule K-1's before the personal tax return due date. 

C Corporation Tax Returns: Effective with the 2016 tax year, there are new deadlines for filing corporate tax returns on Form 1120, depending on the corporation's

  • If fiscal year-end is December 31, the new deadline for 2018 returns: April 15, 2019. 
  • Fiscal year-end other than December 31 is the 15th day of the 4th month after year end

How Tax Return Due Dates are Determined Each Year

If the tax return due date falls on a weekend or holiday, the due date is moved to the first following work day. Here are two examples:

  • if April 15 is on Sunday, the due date is Monday, April 16.
  • If April 15 is on a Saturday, the due date is Monday, April 17.
  • In some years, Monday, April 15 is a holiday in the District of Columbia, so the due date is Tuesday, April 16. 

More Details on 2018 Business Tax Return Due Dates

Here is a list of the types of business entities and their tax return due dates for 2018 tax returns, due in 2019:

Sole Proprietorship

A business is an extension of the person running the business, so its year-end is December 31, and the tax return due date is the same as the individual's - April 15 in 2019. Sole proprietor businesses file their on, which is part of the group of forms and schedules that go along with the person's personal tax return.

The due date for 2018 is April 15, 2019. The Schedule C is filed with the owner's individual tax return (Form 1040).

Single-member LLC

A (that is, an LLC with only one owner) is taxed like a sole proprietorship, using to calculate , so the tax returns are due and taxes are payable on , for the prior year. The due date for 2018 Schedule C forms, along with the owner's personal tax return, is April 15, 2019.


A return is filed as an on , and tax is owed on the individual partner tax return. Form 1065 is now due on 15th day of the 3rd month after the end of the partnership's tax year.

For a December 31 year-end, the due date is March 15. For 2018 tax return filing, the partnership return due date is March 15, 2019. March 15 is also the due date for Individual partners to receive  showing their individual share of the partnership income or loss, to be filed in April on their .


are often taxed as partnerships. If this is the case, the partnership filing and payment regulations above apply, including the March 15, 2019, deadline for giving partners their .

If the multiple-member or S corporation, the due date for the tax status applied. 


A that has not filed a election may choose any convenient date as their year-end (usually a quarter-end date). For the 2018 tax year, c are due and taxes are payable on the 15th day of the fourth month after the end of the company's fiscal (financial) year. For example, a corporation with a year-end date of December 31 must file and pay taxes by April 157, 2019.

Subchapter S Corporation 

Corporations which have filed a election are taxed on the individual income tax returns of the owners. The is filed on Form 1120-S, and the individual owners receive a showing their distributions from the corporation. 

An S corporation must usually take a calendar year end date (December 31) unless the corporation can establish a reasonable business purpose for a different date. The filing date and tax return due date are the same as for other corporations (March 15, 2019, for a 2018 December 31 tax year end.) 

Source for 2016 due date changes: