Inter-office service taxation: clarifies ITC distribution, invoicing, and valuation rules for distinct persons under GST. Where a Head Office procures common input services for itself and branch offices, it may either distribute input tax credit using the Input Service Distributor mechanism (with mandatory ISD registration if chosen) or issue tax invoices to branch offices so they can claim ITC; distribution or invoicing is permissible only if the services are attributable to or actually provided to the branch. For internally generated supplies, the invoice value is deemed open market value when the recipient is eligible for full ITC irrespective of included cost components, and salary costs need not be mandatorily included where full ITC is not available to the recipient.