Watch for these important tax deadlines coming up September 15th:

• Last day to file 2005 corporate returns. Applies to calendar year corporations, both S and C types.
• Third estimated tax payments are due. Applies to both indivduals and C Corporations.

Summary calendar

“C” Corporations (whose FYE = 12/31*)
#1: April 15
#2: June 15
#3: September 15
#4: December 15

Individuals
#1: April 15
#2: June 15
#3: September 15
#4: January 15

From the IRS tax calendar - Third quarter:

Individuals. Make a payment of your 2006 estimated tax if you are not paying your income tax for the year through withholding (or will not pay in enough tax that way). Use Form 1040-ES. This is the third installment date for estimated tax in 2006. For more information, see Publication 505.

Corporations. File a 2005 calendar year income tax return (Form 1120 or 1120-A) and pay any tax, interest, and penalties due. This due date applies only if you timely requested an automatic 6-month extension. Otherwise, see March 15.

S corporations. File a 2005 calendar year income tax return (Form 1120S) and pay any tax due. This due date applies only if you timely requested an automatic 6-month extension. Otherwise, see March 15. Provide each shareholder with a copy of Schedule K-1 (Form 1120S) or a substitute Schedule K-1.

Corporations. Deposit the third installment of estimated income tax for 2006. A worksheet, Form 1120-W, is available to help you estimate your tax for the year.

If you do not know how much to pay

Ask your CPA if you don’t know how much you’re supposed to pay. Typically this information is part of the semi-annual tax planning process.

How to pay

Most corporations pay by mailing in coupons or through electronic funds transfer, the latter of which is required once the company’s tax payments reach a certain size.

Individuals can make payments through coupons or through their W-2 paychecks. Please see “Paycheck as a Financial Tool” for more information about this.

An online tax deadline calendar: IRS General Tax Calendar.

Many CPAs subscribe to tax deadline calendars that are a little more readable. Here’s one example: Tax Due Dates.

*These are dates for federal estimated tax payments for calendar year (FYE 12/31) corporations. Your company’s payment schedule might differ if it’s not on the calendar year or your state’s schedule doesn’t conform to the federal schedule.