Shopify invoice numbering: the order number is not an invoice number

What Shopify does by default

Every order gets a sequential number — #1001, #1002 — the moment it's placed. That number isn't an invoice number, and the order confirmation email isn't an invoice: Shopify's core admin has no invoice generator and no invoice numbering sequence at all. The order number tracks orders, not the fiscal documents supposed to follow them.

What to check

Most places that require invoices require the number to be sequential and gapless — no skips, no reuse, one continuous series. A deleted order, or documents issued by hand in whatever tool was open, can break that silently. One agency, describing what they actually needed from an app for a client's shop, put it plainly: invoices generated "exactly like the order confirmation... plus the legal bits — a continuous number, merchant details." The confirmation email has never been that document. Does whatever produces your invoices today keep one unbroken series, separate from the order number?

What goes wrong at month end

An accountant or a VAT return asks for the invoice sequence and finds a gap, a duplicate, or a count that doesn't match the number of paid orders — and the order that caused it may be weeks old by then.

Check your last month, free

Plain checks a month of paid orders against every invoice, receipt and credit note that actually went out, and names the gaps. One page a month: every order, every document, every gap.

Plain is a technical aide, not legal or tax advice; your accountant or tax authority decides.