ACA Enrollment Extension Act - Amends the Patient Protection and Affordable Care Act to revise the initial open enrollment period provided by a health care exchange so that the period closes on a date that is the later of: (1) May 31, 2014, or (2) a later date determined by the Secretary of Health and Human Services (HHS) after considering the progress made on improving the functionality of the federally-facilitated health insurance marketplace and related factors.

Provides similar terms for initial or special enrollment periods applicable to other health insurance coverage in the individual market.

Amends the Internal Revenue Code to exempt individuals, for taxable year 2014, from the penalty for not maintaining minimum essential coverage for any month ending prior to the enrollment period closing date determined by the Secretary under this Act.