Ministry of Finance twitted about the extension of due date of filing Tax Returns to September 7, 2015.
The extension was first only for Gujarat as the normal life had been disrupted due to riots. But as it happens every year the Income Tax Return Filing website went down on the last date. Due to this many people were not able to file their return within due date.
As e-filing is catching up and government was late in releasing ITR Forms, they are being lenient with timelines. But may be from next year you would be better off filing your tax returns before due date.
Here are some posts which can help you with e-filing of ITR 2015: