April 15th is the tax deadline everyone thinks about, but if you have an S-Corp or C-Corp those returns are due on March 15th. S-Corps should file form 1120S by March 15th and provide each stockholder with a K-1 by that date. There is no tax due with an S-Corp return. C-Corps must file form 1120 by the 15th of March and must also pay their corporate income tax by that date.
Both types of entities can request an automatic 6 month by filing a Form 7004. If you are a C-Corp the extension does not give you more time to pay your tax and you should make a payment of any balance you estimate might be owed by the corporation by the 15th.
Another S-Corp deadline is on March 15th. If you are newly electing to be an S-Corp in 2011, you need to file the request for S-Corp status (Form 2553) by March 15. If Form 2553 is filed before March 15th, the S-Corp election will be effective for the entire tax year of 2011.
So don’t put everything off until April 15th, because your business may need to file a tax return on March 15th.