What does Minimum Alternate Tax (MAT) entail in India?

All companies declaring low or zero profits are subject to the MAT. Presently, MAT is levied at 18.5 percent of book profits plus the applicable surcharges and education cess. The MAT is levied on companies whose tax payable under normal income tax provisions is less than 18.5 percent of book profits. Additionally, MAT is applicable to Special Economic Zone (SEZ) developers and units for income arising on or after April 1, 2012.