For MBA, there are eight major exams that are held in India and conducted by different institutional bodies. I will describe each of them in brief :

1.) CAT- Common Admission Test. This is how MBA in India is generally known as. Conducted by IIMs every year, this is considered to be the forth toughest exam in India after the the civil services. This exam is an entry seat for Post Graduate Program and Fellow Program of all IIMs and several other B-Schools that consider CAT scores. CAT registration form is released around the first week of September and the exam is conducted in Nov or by the first week of December.

2.) XAT- Xavier's Aptitude Test is conducted for admission to Post-Graduate Programme in Management at XLRI, XISS, XIM, LIBA, etc. Institutes that consider XAT scores are GIM (GOA), XLRI(JAMSHEDPUR), XIMB,  SIBM(PUNE), BIM(TRICHY). Online registration begins from second week of August and is available till first week of December (tentatively). Exam is usually conducted in the first week of January.

3.) NMAT by GMAC- This exam is conducted by Narsee Monjee Institute of Management. Institutions accepting its scores are NMIMS University (Mumbai, Bangalore, Hyderabad), Alliance University Bangalore, Amity University Delhi and 15 other colleges. Registration begins in the first week of July and can be scheduled over three seatings. Registration ends around the second week of October. And you can deliver the exam on your suitable date (among the ones provided)  between the second week of October to the second week of December.

4.) IIFT- Indian Institute of Foreign Trade conducts this exam every year exclusively for admission into its institute in IIFT DELHI AND IIFT Kolkata. You can obtain offline application form too by the first week of September and its online registration too ends by first week of September. It begins its registration by the first week of July. Exam is usually conducted in the last week of November.

5.) SNAP - Symbiosis National Aptitude Test is a common written test for the admission processes of all Symbiosis autonomous postgraduate institutes. Institutes that accept SNAP scores are SIBM PUNE, Bangalore and Hyderabad, SICSR, SIMC(PUNE), SIIB, SCMHRD, SIMS, SITM, SCIT, SIOM(NASHIK) , SIHS, SSBF, SSMC(BANGALORE). Registration usually begins from second week of August and ends by second week of November. Exam is usually conducted in the second week of December.

6.) CMAT- This exam is conducted by All Indian Council for Technical Education (AICTE) and it relases its form around by first week of November. Last date for registration is around the first week of December and exam is conducted around the last week of January.

7.) MAH-CET - This is management entrance exam conducted for admission in PGP programme of B-Schools exclusively in Maharashtra. Last date of registration for this exam is around second week of February.

8.) MAT- Management Aptitude Test is conducted by All India Management Association for admission in various institutes (Around 300+ B-Schools accept MAT scores). MAT is held four times a year : February, May, September, December.  Registration for MAT February is open now.

Hope this helps and guides you.

Wish you all the best for your future!!