Today’s the deadline for filing partnership and S-Corporation returns. An extension is available by filing Form 7004. Most (but not all) states grant an automatic extension. Do realize that if your state charges a tax for your entity (i.e. New York and Illinois), you need to pay that tax even if you file an extension.
There are two other deadlines today. Form 1042-S (report of withholding of foreign individuals) must be filed today, either electronically using the IRS’s FIRE system or by mail. Also, Form 3520-A (Annual Information Report of Foreign Trusts) is due today. An extension is available for Form 3520-A by mailing in Form 7004 (Part III, Code 27). There are ridiculous penalties for late-filing Form 3520-A, so if this applies to you and you’re not ready mail that extension (certified mail, return receipt requested) today.