Input Service Distributor credit allocation requires issuance of distribution document and pro rata allocation by turnover. Input Service Distributor must allocate input tax credit by issuing a prescribed document; distribution is limited to available credit and may be made only to recipients against prescribed details. Credit attributable to a single recipient goes solely to that recipient; credit attributable to multiple recipients is apportioned pro rata by each recipient's turnover in the State or Union territory during the relevant period, and only to recipients operational in the current year during that period. Relevant period and definitions of recipient and turnover are specified for measurement.