Why Are There Missing or Skipped Invoice Numbers in Recurly?

Missing or skipped invoice numbers in Recurly are a direct result of unsuccessful subscription sign-ups.

Here’s why this occurs:

Our system assigns a unique invoice number and queues an invoice at the time of checkout to send it to your payment gateway along with the transaction. If the initial sign-up attempt is unsuccessful (e.g., due to a payment decline), the subscription and its corresponding invoice are not created. Only the transaction attempt itself is recorded.

Because that unique invoice number was already sent to the gateway during the failed transaction attempt, we cannot reuse it. Attempting to do so would result in a gateway decline, as it would be considered a duplicate invoice number. Therefore, Recurly must "skip" that number and utilize the next available number in the sequence for the next successful invoice.