What is Tonnage Tax??

Tonnage tax is a special scheme of taxation for shipping companies.  A shipping company can pay its tax as per this scheme instead of Section 28-43C subject to fulfillment of certain conditions.  It's an optional scheme.

Section 115 VA-115VZC  of Income Tax act governs the provisions of the scheme.

As per scheme tax is levied on the basis of aggregate of tonnage income (its capacity) of ship.  Hence its called tonnage tax.

For detailed study refer following link of income tax department

https://law.incometaxindia.gov.in/TaxmannDit/Displaypage/dpage1.aspx?md=2&typ=cn&yr=2009&chp=381