Reversal of input tax credit where consideration unpaid after prescribed period; attracts interest and is restored on payment. Rule 37 requires reversal of input tax credit where a registered person who availed ITC on inward supplies (other than reverse charge supplies) fails to pay the supplier the consideration within the prescribed time limit; the person must reverse an amount equal to the ITC availed, proportionate to unpaid value, and pay interest while furnishing FORM GSTR-3B for the tax period following the specified period from invoice issue, with re availment permitted on subsequent payment and certain supplies deemed paid for the time limit purpose.