Although an official release date has yet to be revealed, according to EA, The Sims 4 will most likely be released this September. The title was originally scheduled to be released this Spring, but Maxis and EA announced back in October that the release date had been pushed back, with neither revealing the reason for the delay.
The Sims 4 is now scheduled to release this Autumn, which means, any day between the 22nd of September and 20th of December. However, The Sims 4 appeared in the recent EA fiscal Q2 release, with EA's Q2 ending on the 30th of September. This means that if this information is correct, the title will be released between 22nd of September and the 30th of September.
Considering that games are usually usually released on Tuesdays in North America, and on Fridays in Europe, The Sims 4 will probably be released on the 23rd of September in North America, and on the 26th of September in Europe. Whether this is true or not, EA will certainly reveal the release date at E3.
The life simulator is now available for pre-order on the game's official site, and by doing this players will get a free upgrade to the Limited Edition, which include the Life of the Party content.