Invoicing & myDATA
The Invoicing module lets you create invoices and credit notes, keep them in the numbering series Greek law requires, produce a printable PDF, and transmit each document electronically to the tax authority (AADE) through myDATA.
Invoicing is part of the Business plan. Open it from eCommerce → ERP in your WordPress admin, then choose Invoices in the sidebar.
Invoicing is one of the ERP modules included in the Business plan. See Plans & Features for the full comparison and how to upgrade from Starter.
Before you start
Set these up once, so your first invoice is valid and ready to transmit:
- Your company details. Go to ERP → Settings → General and fill in your Company Name, VAT Number (ΑΦΜ), Tax Office (ΔΟΥ) and address. These appear on every invoice as the issuer, and an invoice cannot be issued until your VAT number is filled in.
- At least one invoice series (see Invoice Series below) — this decides both the numbering and the document type.
- myDATA credentials, if you want to transmit electronically (see AADE myDATA).
Invoice Series
An invoice series is a numbering sequence tied to a specific document type. Every invoice belongs to a series, and the series is what determines:
- the type of document (sales invoice, service invoice, credit note, retail receipt, and so on), and
- the number each new invoice receives.
Manage your series under ERP → Settings → Invoice Series.
Creating a series
Click + New Series and fill in:
| Field | What it does |
|---|---|
| Code | A short label that identifies the series in lists (for example A, TIM, APY). |
| Name | A friendly name (for example Sales Invoices). |
| Invoice Type | The myDATA document type this series produces — grouped into Sales, Services, Self-billing, Credit Notes, Contracts & Rents, Retail and Expenses. This choice drives how the document is classified and transmitted. |
| Prefix | Optional text placed in front of the number (for example INV-). |
| Next Number | The next sequence value. Numbers are padded to five digits, so a prefix of INV- starting at 1 produces INV-00001, then INV-00002, and so on. |
| Default Series | Marks this series as the one pre-selected when you start a new invoice. |
| Active | Only active series can be used for new invoices. Turn a series off to retire it without deleting its history. |
Create one series per document type you actually issue — for example a Sales Invoices series (type 1.1) and a Credit Notes series (type 5.1). You choose the series when you create each invoice, and the correct type follows automatically.
A series that already has invoices against it cannot be deleted — this keeps your numbering history intact. Retire it with the Active switch instead.
Creating an invoice
- Go to Invoices → New Invoice.
- Choose the Series. The document type is set by the series, so pick the series that matches what you are issuing.
- Choose a Payment Method and, if relevant, a Due Date.
- Select the customer: search by name, email or VAT number to link an existing customer, or click + New to create one. You can also type the counterpart's name, VAT number and address by hand.
- Add line items. For each line enter a description, quantity, unit, unit price and an optional discount, then pick the VAT rate. The net, VAT and total are calculated for you.
- Click Save as Draft to keep working on it later, or Save & Issue to finalise it immediately.
VAT rates
Each line carries a VAT category. The available rates are:
| Rate | Notes |
|---|---|
| 24% | Standard rate |
| 13% | Reduced rate |
| 6% | Super-reduced rate |
| 17% / 9% / 4% | Reduced island rates |
| 0% | Zero-rated |
| Exempt | VAT-exempt |
The invoice summary breaks the total down by VAT rate automatically.
myDATA classification
myDATA requires each line to carry an income (or expense) classification. For most document types the system fills in the correct classification for you based on the series' invoice type. If you need to change it on a specific line, open the Class. panel on that line and adjust the category and E3 type — only the options that are valid for that document type are shown.
Invoice statuses
An invoice moves through a simple lifecycle, shown as a timeline at the top of the invoice:
- Draft — still editable. You can change every field, or delete it entirely.
- Issued — finalised and numbered. It can no longer be edited, a PDF is available, and it is ready to transmit to myDATA.
- Transmitted — successfully sent to myDATA and stamped with an official MARK (see below).
- Cancelled — voided (see Cancelling an invoice).
You can filter the invoice list by status and search it, and each row shows both the invoice status and its myDATA state at a glance.
Credit notes
To issue a credit note, create an invoice under a series whose type is a credit note type (for example 5.1 — Credit Note, or 11.4 — Retail Credit Note for retail). You fill it in and issue it exactly like any other invoice, and it transmits to myDATA the same way.
Record the details of the original document (its number and date) on the credit note's lines or notes so the correction is clearly traceable.
Downloading the PDF
Once an invoice is Issued or Transmitted, a Download PDF button appears on the invoice. The PDF shows your company details (including your Tax Office / ΔΟΥ), the customer, the line items with their VAT breakdown, and — after transmission — the myDATA MARK.
AADE myDATA
For Greek businesses, every issued invoice must be reported electronically to AADE (the Independent Authority for Public Revenue) through myDATA. The module handles this for you.
Setting up the connection
Go to ERP → Settings → myDATA and enter:
- User ID (ΑΦΜ) — the VAT number registered with myDATA.
- Subscription Key — the key issued to you from the AADE myDATA portal for your subscription.
- Environment — choose Sandbox to test safely (nothing is sent to the live tax system) or Production for real, legally binding transmissions.
Then click Test Connection to confirm your credentials reach the AADE servers before you rely on them.
Choosing Production means every transmission is sent to AADE and is legally binding. Set up and test in Sandbox first.
Transmitting an invoice
After an invoice is Issued:
- Open the invoice (or use the invoice list) and click Transmit to myDATA.
- The document is sent to AADE and, on success, is stamped with a MARK — the official unique identifier assigned by myDATA. The invoice moves to the Transmitted status.
- Alongside the MARK, the invoice records the myDATA UID, an authentication code, and a View on myDATA link (the official QR/verification link).
Because transmission talks to AADE and can take a moment, you will see a confirmation when it finishes — whether it succeeded or failed — even if you have moved to another screen in the meantime.
The invoice list shows each document's myDATA state in its own column:
| myDATA state | Meaning |
|---|---|
| Transmitted (with MARK) | Successfully reported to AADE. |
| Pending / — | Issued but not yet transmitted. |
| Error | A transmission was attempted but AADE rejected it — the reason is shown on the invoice so you can fix it and try again. |
| Cancelled | The document has been cancelled in myDATA. |
Before transmitting, you can click Preview XML on an issued invoice to see exactly what will be sent and to catch any validation problems up front.
You transmit each invoice yourself with the Transmit to myDATA button. An Auto-transmit on issue option is shown on the myDATA settings screen, but it is not active yet — for now, transmit your invoices manually after issuing them.
Cancelling an invoice
Use the Cancel button on an issued or transmitted invoice to void it:
- If the invoice has already been transmitted (it has a MARK), cancelling also cancels it in myDATA and records a cancellation MARK.
- If it was issued but not transmitted, it is simply marked cancelled locally.
Draft invoices are not cancelled — delete them instead.
Invoicing and your accounts
When you issue a sales invoice, it posts to your general ledger automatically — a debit to Customers and a credit to Sales, plus VAT on sales where applicable. There is nothing separate to record. See Accounting for how these automatic entries work.
This page describes WP eCommerce Core 9.8.0. Because the ERP shares your store's database, your invoices, customers and accounts all work from the same data — there is nothing separate to sync.