Learning Center

September 2018 Business Due Dates

September 17 - S Corporations

File a 2017 calendar year income tax return (Form 1120S) and pay any tax due. This due date applies only if you requested an automatic 6-month extension. Provide each shareholder with a copy of K-1 (Form 1120S) or a substitute Schedule K-1.

September 17 - Corporations 

Deposit the third installment of estimated income tax for 2018 for calendar year

September 17 -  Social Security, Medicare and withheld income tax

If the monthly deposit rule applies, deposit the tax for payments in August.

September 17 - Nonpayroll Withholding



If the monthly deposit rule applies, deposit the tax for payments in August.

September 17 - Partnerships

File a 2017 calendar year return (Form 1065). This due date applies only if you were given an additional 5-month extension. Provide each partner with a copy of K-1 (Form 1065) or a substitute Schedule K-1.

September 17 - Electing Large Partnerships 

File a 2017 calendar year return (Form 1065-B). This due date applies only if you were given a 6-month extension. March 15 was the due date for furnishing Schedules K-1 or substitute Schedule K-1 to the partners.



Share this article...

Want tax & accounting tips and insights?

Sign up for our newsletter.

I confirm this is a service inquiry and not an advertising message or solicitation. By clicking “Submit”, I acknowledge and agree to the creation of an account and to the and .

Our Offices

Christopher J. Keiluhn, Cpa Llc

45 E. City Ave, Bala Cynwyd, Pennsylvania 19004

Conshohocken Office

101 E. 8th Ave, Suite 205 Conshohocken, Pennsylvania 19428

Philadelphia Office

1500 Chestnut St. Suite 2 #1105 Philadelphia, PA 19102

Egg Harbor Office

2600 Tilton Rd. #1015 Egg Harbor Township, NJ 08234

New York Office

442 5th Ave #1325 New York City, NY 10018

Miami Office

1000 Brickell Ave Suite 715 #1031 Miami, FL 33131

Atlanta Office

Atlanta Financial Center 3343 Peachtree Rd NE Suite #145 Atlanta, GA 30326

Austin Office

1401 Lavaca St #509 Austin, TX 78701