Shakespeare’s words don’t apply just to Julius Caesar; they also apply to calendar-year partnerships, S corporations and limited liability companies (LLCs) treated as partnerships or S corporations for tax purposes. Why? The Ides of March, more commonly known as March 15, is the federal income tax filing deadline for these “pass-through” entities. Not-so-ancient history Until the 2016 tax year, the filing deadline for partnerships was the same as that for individual taxpayers: April 15 (or shortly thereafter if April 15 fell on a weekend or holiday). One of the primary reasons for moving up the partnership filing deadline was to make it easier for owners to file their personal returns by the April filing deadline. After all, partnership (and S corporation) income passes through to the owners....