Everyone seems to know that April 15th (actually 18th this year) is the tax deadline but many business owners don’t realize that March 15th is the corporate deadline.  This includes both regular corporations, S corporations, and LLC’s that are taxed as S corporations.  Partnerships have until the individual tax deadline of 4/18 to file. 

You can always extend, but the tax or estimated tax at least, is due on the regular due date, not the extended one.  Aren’t sure you have the funds to pay all of it in… at least file an extension anyway and pay as much as you can.  The penalties are much stiffer if you don’t!