C Corporations have the drawback of having different filing deadlines from other returns—even other corporate returns. Therefore, they run the risk of being filed late.
Form 1120 & C Corporations
C Corporation tax returns are filed using Federal Form 1120, in addition to any state tax forms which certain states require. Be aware that, in such cases, a state return must be filed with income apportioned for nexus, attached to the income tax. All this must be considered in time for the due date—usually three and a half months after the end of the fiscal year. If that deadline cannot be met, the C Corporation must file Form 7004, to request an extension. Fortunately, the very nature of a C Corporation allows for the taxpayer to choose its end of calendar year. It gives the flexibility to plan for tax payment, or perhaps an unforeseen boost in business which changes income, and therefore tax.
C Corporation End of Year
All this being said, do not confuse the end of calendar year with the less-conventional tax year. C Corporations which claim the last calendar day of the year as their end of fiscal year—all the way to the end of January of the following year!—would be required to file Form 1120 of the December year date. Strangely enough, claiming year’s end at the end of November actually involves filing Form 1120 of the preceding year.
Clarity on which tax year is claimed is of paramount importance. Tax laws change from year to year, so new laws could apply to the C Corporation in question, depending on the tax year it claims, based on its end of calendar year.