For S Corporations, Partnerships, and LLC's with more than one member: March 15th – can be extended until September 15th.
For C Corporations: the 15th day of the 4th month following year end – can be extended for 5 months. (For calendar year end C corps, the due date is April 15 and can be extended until September 15th.)
For Sole Propreitorships and LLC's that file as sole proprietors: April 15th – can be extended until October 15th.
Penalties & Interest
C Corp penalties for filing late: 5% of the balance due per month, not to exceed 25%. (So, if there’s no balance due, there’s no penalty for filing late.)
The penalty for paying late after March 15th): .5% (one half percent) of the balance due per month.
S Corp penalties for filing late: $220 per shareholder per month.
Partnership penalties for filing late: $220 per partner per month.
