Vat dealer to gst composition dealer

Refer Sec 18(4) of CGST Act for more clarification.

Sec 18(4) states that 

Where any registered person who has availed of input tax credit opts to pay tax under section 10 or, where the goods or services or both supplied by him become wholly exempt, he shall pay an amount, by way of debit in the electronic credit ledger or electronic cash ledger, equivalent to the credit of input tax in respect of inputs held in stock and inputs contained in semi-finished or finished goods held in stock and on capital goods, reduced by such percentage points as may be prescribed, on the day immediately preceding the date of exercising of such option or, as the case may be, the date of such exemption:

Provided that after payment of such amount, the balance of input tax credit, if any, lying in his electronic credit ledger shall lapse.

Either i m not getting ehat you want to ask or you are misinterpreting the Sec.