Hi @llubbo18,
Yes, it is. You can set the order number as the invoice number under WooCommerce > PDF Invoices > Documents > Invoice > Display invoice number.
However, our recommendation is to use the invoice numbering instead. Since in most countries there’s a hard requirement for invoice numbers to be sequential without any gaps, to use the invoice numbers in the sequence (keep them separated) is crucial to comply to it. If you use the order number as invoice number there may be gaps, since the orders are numbered in the main WordPress post numbering system used by posts, pages, images, orders, coupons, products, etc.
So if you create a new product between when two orders are placed, and upload an image for that product too, the order number will not sequential (if the first order was #100, the product would be #101, the image #102 and the next order #103). See?Invoice numbers explained.
Hope it makes sense!
