E-invoicing is the issuing, transmission and receipt of invoices in a structured electronic format that allows automatic processing. The defining feature is that every field — the VAT number, each line item, the totals — sits in a defined, labelled place, so the receiving system can book the invoice without anyone retyping it.
This is narrower than everyday usage suggests. Emailing a PDF is not e-invoicing in the regulatory sense, because a PDF is a picture of an invoice as far as software is concerned. Formats that do qualify include XML-based ones such as UBL, and hybrid formats such as Factur-X and ZUGFeRD that embed structured XML inside a human-readable PDF.
Why It Matters
The distinction has become a legal one rather than a technical preference. A growing list of countries now require structured e-invoices for domestic business-to-business trade, with deadlines phased by company size through the late 2020s. Businesses that treat "we email PDFs" as compliance discover otherwise when a mandate reaches their size bracket — and the obligation to *receive* structured invoices typically arrives before the obligation to issue them.
Example
A supplier issues an invoice as a Factur-X file. The client’s accounts payable team opens it and sees an ordinary PDF. Their accounting system, meanwhile, reads the XML embedded inside the same file and creates the payable automatically — correct supplier, correct amounts, correct tax, no typing and no transcription error.
Frequently Asked Questions
Is emailing a PDF invoice considered e-invoicing?
Not under the mandates. A PDF is unstructured, so software cannot reliably extract its fields. Hybrid formats like Factur-X and ZUGFeRD solve this by embedding structured XML inside the PDF, giving you one file that satisfies both a human reader and a validator.
Do I need special software to send e-invoices?
You need something that can produce the required structured format, and in some countries something that can transmit it over a specified network or platform. Many accounting packages now include this; elsewhere it comes from a service provider.