Last week, the Central Board of Secondary Education (CBSE), which will conduct the exam, had announced that the offline test would take place on April 7, 2013, while the online tests will be held between April 8 and April 30 next year. Students can choose to write the test in either mode.
“The number of attempts which a candidate can avail JEE (Main) shall be limited to three for all the candidates in consecutive years,” said the document.
Those who finished Class 12 in 2011 or 2012 will also be eligible to appear for next year’s exam, in addition to the 2013 batch. The document also clarifies that students will be able to improve their Class 12 board exam performance, since these marks will also carry weightage from next year.
According to the new document, the three-hour exam will have objective type questions and multiple-choice questions. For each wrong answer, one-fourth of a mark will be cut, but there will be no deductions for not attempting.
P.S. I couldn't find official confirmation on any government site regarding this.