1. Deadlines for Income Tax Returns
2. Deadlines for Quarterly Tax Returns and Unemployment Filing
3. Extended Due Dates

When are S-corp taxes due? Due dates depend on the type of taxes your S-corporation is paying, with differences between an annual tax return and returns for employee payroll. You're usually able to extend deadlines if needed.

Deadlines for Income Tax Returns

For most S-corps, March 15 is the deadline for filing a yearly tax return. Due dates are three months after the end of the company's tax year, with the specific day being the 15th of the month. 

However, not all businesses have the same fiscal year. For example, an S-corp with a December 31 year end has a March 15 deadline of the following year. A S-corp with a fiscal year end of August 31 has a November 15 filing deadline of the same year.

S-corps must report all company financial activity on form 1120S. They must also attach a Schedule K-1 for every company shareholder. Shareholders in an S-corp have the same deadline as individual taxpayers, since they're reporting their Schedule K-1 (or their portion of the company's taxable income) on their personal tax returns. This deadline is April 15.

The business can file form 7004 with the IRS to get a six-month filing extension. A due date of September 15 only applies if a business asks for a six-month extension.

Deadlines for Quarterly Tax Returns and Unemployment Filing

For an S-corp with employees, the company withholds certain taxes from employee paychecks. This includes the following: 

Every quarter, the S-corp is responsible for filing form 941. This reports the amount withheld each quarter and must be remitted to the IRS. Along with reporting quarterly wages, federal income tax withholdings, Social Security, tips, and Medicare taxes withheld, form 941 also reports adjustments to Medicare taxes and Social Security, as well as the COBRA credit.

An S-corp with employees may also be responsible for filing form 940, or a Federal Unemployment Tax Return. The form reports the amount of wages for which the company owes unemployment taxes. 

Federal unemployment taxes, also called FUTA, that are more than $500 in a quarter must be paid. Typically, an S-corp files form 940 if at least one of the following conditions is met:

  • The company employs at least one person who works at least a portion of a day 20 weeks or more.
  • It pays $1500 in wages in a quarter.

The deadline for filing form 940 is January 31.

The IRS grants extensions to S-corps that pay the entire tax on time. S-corps have until February 10 to file in those cases.

Extended Due Dates

Following are some of the forms an S-corp may file, their purpose, and due date extensions the company may request.

  • Forms 1040, 1065, and 1120S: Six months, beginning on the filing due date
  • Form 1041: Five and a half months, starting on the filing due date 
  • Form 1120: In general, six months beginning on the filing due date 
  • Form 3520 (Yearly report of receipt of foreign gifts and transactions with foreign trusts): Maximum extension is six months, ending on October 15 
  • Form 3520–A (Yearly information return of a U.S. owner's foreign trust): Maximum extension of six months 
  • Form 990 series (Organizations exempt from income tax): Six months from the filing due date 
  • Form 4720 (Excise tax returns): Six months from the filing due date 
  • Form 5227: Six months from filing due date 
  • Form 6069 (Excise tax returns): Six months from filing due date
  • Form 8870: Six months from filing due date

While it may seem like there are many dates to remember, your S-corp typically won't need to remember all of them. Only concern yourself with the forms and deadlines that pertain to your particular business. For instance, S-corps with many employees have forms to file that an S-corp with no employees doesn't have to worry about.

What's most important is adhering to the deadlines. The IRS can issue penalties when you don't file on time. You can always request an extension if needed. Having a person inside or outside of the company who's solely responsible for tax issues is a good way to make sure you meet your federal tax return obligations.

If you need help with business taxes for an S-corp or other business type, you can post your legal need on UpCounsel's marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with or on behalf of companies like Google, Menlo Ventures, and Airbnb.