Everybody knows April 15th is tax day. Most people fear it and spend lots of hours worrying about it. It’s fair to say that only tax preparers and the IRS look forward to the day, leaving the general public to sweat it out weeks beforehand.

The truth is, April 15th is not the only “tax day” to be aware of when you run your own business. The IRS has many deadlines throughout the year for businesses to consider.

For example, if a C Corporation expects to make a certain amount of money over the course of the year, it will owe estimated taxes for that year in quarterly installments. In 2009, any C Corp expecting to owe at least $500 in taxes for the year was required to file estimated taxes for each quarter. Individuals can owe quarterly estimated taxes as well; these are usually withheld from the paychecks of salaried employees. If you are self-employed, however, you may owe an individual quarterly estimated tax return in addition to your corporation’s. LLCs and S Corps don’t file estimated tax — their profits flow through to the shareholders, who pay estimated tax for individuals.

There are additional federal tax requirements for companies that hire employees. These companies have to make quarterly payroll tax payments (Form 941) on a different date from the estimated tax payments. If you are the CEO of a one-person corporation, you have to make payroll tax payments on your own salary, even though you are the only officer and sole shareholder.

Typically, an employer must also give a Form W-2 to its employees and to the IRS a few months before tax season begins.

If for some reason you can not file your corporate tax return on time, the IRS grants extensions on the return. This requires an additional filing (Form 7004), which has its own deadline. Although corporations and LLCs use the same form for this extension, corporations receive a 6 month extension, while LLCs receive only a 5 month extension. Individuals who miss the April 15 deadline receive an automatic 6 month extension.

If the filing schedule seems overwhelming to you, don’t worry. Below is a summary of the major filing dates for the IRS which generally affect all business owners. Remember that, depending on which type of entity you own, the due date for the tax return may be different (for example, the tax return deadline for corporations and LLCs differs by one month). Also, each state has its separate filing deadlines in addition to the federal deadlines listed below. Make sure to check these as well.

Federal (IRS) 2010 Filing Deadlines

Month	Day	Filing
January	15	Quarterly estimated tax payment for individuals (Form 1040-ES)
February	1	Employers give W-2s and 1099s to employees and independent contractors for 2009
	1	File Form 941, employers quarterly employment taxes for Q4 of 2009
March	1	File information returns for W-2s and 1099s sent to workers on February 1st with IRS (mail deadline only – see E-file deadline below)
	15	C and S Corporation returns due (1120 and 1120S, respectively) to IRS
	31	E-file deadline for filing W-2s and 1099s with IRS
April	15	Individual tax return due (Form 1040)
	15	Partnership/LLC tax return due (Form 1065)
	15	Corporate estimated tax due for Q1 for corporations (Form 1120-W)
	30	File Form 941, employers quarterly employment taxes for Q1 of 2010
June	15	Quarterly estimated tax due for Q2 for individuals (Form 1040-ES)
	15	Quarterly estimated tax due for Q2 for corporations (Form 1120-W)
August	2	File Form 941, employers quarterly employment taxes for Q2 of 2010
September	15	Quarterly estimated tax due for Q3 for individuals (Form 1040-ES)
	15	6th month extension deadline for C and S Corporation returns and 5th month extension deadline for partnerships/LLCs (Form 7004
October	15	6 month extension deadline for individuals filing Form 1040
November	1	File Form 941, employers quarterly employment taxes for Q3 of 2010
December	15	Quarterly estimated tax due for Q4 for corporations (Form 1120-W)