Issuing invoices for orders by hand is work a computer does better, faster and without typos in the VAT number - and automating it takes hours, not weeks. The target flow is simple: the customer pays, the invoice is issued automatically in your invoicing software, the customer gets it by email, and accounting sees everything on their side. No retyping, no “I’ll send the invoice after the weekend”.
How it fits together
The store does NOT issue invoices - the store passes data across. The invoice is issued by the invoicing system: Fakturownia, iFirma, inFakt, wFirma or an ERP. They connect to WooCommerce through that system’s official or well-tested plugin, which on a chosen event (most often: the order being paid) creates the document from the order data and sends the PDF back to the customer.
That split of roles became doubly important with KSeF, Poland’s national e-invoicing system: it is the invoicing software that talks to the state system, not WordPress. The store’s job is to supply complete and correct data - and that is most of a successful rollout.
The configuration that actually works
- A VAT number field in checkout with format validation plus a “buying as a business” checkbox. Without it the automation cannot tell a company invoice from a personal one
- Trigger the invoice on payment, not on order placement - otherwise cash on delivery and abandoned payments produce ghost invoices to correct later
- VAT rate mapping - products at 23%, 8%, exempt; shipping as a separate line with the correct rate. This is where the errors are born that your accountant finds a quarter later
- Numbering in one place - if you also invoice outside the store (B2B by email, services), every source has to write into one series in one system; two parallel numbering schemes are asking for trouble
- Credit notes on returns - a return in the store should create a credit note automatically, or at least leave a clear trail for a manual one; in e-commerce returns are everyday business, not an exception
- Receipts and personal invoices for B2C - depending on your situation (fiscal printer? exemption?); set it with your accountant once and the automation will stick to the rules
Which system to choose
Honestly: for a typical store the differences matter less than your accountant’s habits. Fakturownia is liked for its flexibility and API, iFirma and inFakt combine invoicing with bookkeeping (handy if you do it yourself), wFirma likewise. If your accounting already runs in one of them, pick the same one; moving an accountant costs more than the feature differences. If the heart of the company is an ERP (Subiekt, Optima), invoicing usually stays there - in that case look at integrating the store with an ERP.
What helps: after configuring it, place three test orders: as a business with a VAT number, as a consumer, and with cash on delivery - then look at all three documents through your accountant’s eyes (rates, dates, numbering, buyer details). Fifteen minutes of testing saves hours of corrections - and that is exactly the quarter of an hour skipped by every broken rollout I have seen.
Frequently asked questions
What does it cost? The cost is made up of: the invoicing system’s subscription, the plugin (often free) and a one-off configuration with testing. I give the exact figure after looking at the store - it depends on what you already have set up. It pays back quickly: the more orders, the faster.
Does the customer get the invoice straight away? Yes, the automation emails the PDF right after it is issued - usually faster than they could ask for it. A small thing that noticeably cuts the number of “please send me an invoice” emails in your inbox.
I already have a plugin generating PDFs in the store - isn’t that enough? A PDF plugin in the store produces a document outside the accounting system and outside KSeF - in 2026 that is not enough. Move to issuing in an invoicing system; the old PDFs stay as an archive.
Would rather not watch over it every month yourself? I take sites and stores under ongoing care - backups, updates, monitoring, and priority when something breaks. Tell me what you run and I will send back scope and price.