In case of continuous supply of goods, invoice should be issued at the time when each payment is received by the supplier or statement of accounts is issued.
Continuous supply of services
In case of continuous supply of services, invoice should be issued:
Where the due date of payment is known in the contract- The invoice should be issued on or before the due date of payment.Where the due date of payment is not known in the contract- The invoice should be issued before or at the time when the supplier receives the payment.Where the payment is linked to the completion of an event- The invoice should be issued on or before the date of completion of the event. For example: A works contract for construction of a building, where payment will be made on completion of each stage of construction. In this case, the invoice should be issued on or before each stage of construction is completed.