Question 1

Difference between order number and invoice number?

Accepted Answer

A purchase order (PO) is the internal document that frames an operation; the invoice is the fiscal document issued for billing. They can have separate numbering.

Question 2

What format should I use?

Accepted Answer

For ecommerce, ORD-YYYYMMDD-#### (prefix, date, sequence) is the most readable. For B2B, PO-YYYY-#### is the standard.

Question 3

Do they need to be sequential?

Accepted Answer

No legal requirement for internal management, but sequential numbers help auditing and traceability.

Order Number Generator