Are we required to issue e-invoice if the transaction is not to capture sales or services? For example, interbranch billing, interco billing, disbursements and reimbursements.

The use of e-Invoice is applicable for transactions between Suppliers and Buyers, encompassing not just sales or revenue but also disbursement and reimbursement amounts.  However, interbranch transactions may be excluded, but intercompany transactions may have to be included.