If you need to generate an invoice to a customer for miscellaneous product or service then the free text invoice is a useful tool. It’s simple in that you only need to specify the description, amount for what you are billing and specify the GL account you want to post this against.

This video gives a basic overview of using the free text invoice.

If you want full document process and sales invoicing with inventory then use the sales order document in AX.

Cheers

Lachlan