WPI's Calendar Year runs from January 1 to December 31. Few events are dependent on the calendar year (e.g., vacation for employees expires with the fiscal year).
Some student organizations have executive boards whose terms run during a calendar year.
Donations made to WPI during the calendar year can count as charitable deductions from that years taxable income. Staff usually work the last week of the year to accomodate last minute donations to the university even though the rest of the university is off.