How do you make invoice numbers sequential per client?

[fbc]

Is there a way to make invoice number sequential on a per client basis? Like {client_num}-{invoice_num}

[twhiting9275]

WHMCS does not support that level of sequential numbering, no. You can utilize sequential numbering, but not on a per-client basis (ie: 1-1000, 2-1000, etc).

[WHMCS ChrisD]

As indicated by twhiting9275 this is not something that we support however you might like to consider adding a feature request to https://requests.whmcs.com/