interest applicable on ITC reversal

The amount of input tax credit shall be added to the output tax liability of the registered person for the month in which the details are furnished.

The registered person shall be liable to pay interest at the rate (18%) for the period starting from the date of availing credit on such supplies till the date when the amount added to the output tax liability,  is paid.

Interest is applicable @ 18% or @ 24% pls clarify.

section 50(1) 

if any person takes undue or excess claim of input tax credit (ITC) then person shall be liable to pay interest at 24% .

CAN I REVERSE MY EXCESS ITC THROUGH DRC-03 IN VOLUNTARY OPTION FROM MY AVAILABLE ITC CREDIT LEDGER, BEFORE THE FILLING OF GSTR-9 OF 2017-18 ????

No In case of Annual Return (GSTR-9) you have to pay the liabilities through cash ledger only