ACT just released the official practice test for the 2015-16 year. The practice test is based on the June 2014 Official ACT test, Form 72C. However, not all questions are identical. For example, in the math section of the practice test, only 36 of the questions are present in the June 2014 ACT test. Here is the link:
This also happens to be the first time that the practice test released by ACT is from a recent administration.
Please note that ACT uses this generic link to post practice tests and the link in the future will point to an updated test.