Inter-office supply valuation: invoice value deemed open market value where recipient claims full input tax credit. For common input services procured by a Head Office from a third party and attributable to the Head Office and one or more Branch Offices, the Head Office may either distribute ITC via the Input Service Distributor mechanism (subject to mandatory ISD registration) or issue tax invoices to Branch Offices so they may claim ITC; such distribution or invoicing is permitted only where the services are attributable to or actually provided to the receiving Branch Office. For internally generated services, when the recipient Branch Office is eligible for full ITC the invoice value is deemed the open market value irrespective of included cost components; if recipient is not eligible for full ITC, HO salary costs need not be mandatorily included in taxable value.