PAY by square QR payment on an invoice: how it works and what goes into it

PAY by square is the Slovak standard for payment QR codes. The client scans it with their banking app and the payment order fills itself in: the account number, the amount, the variable symbol and the due date.^⁠[1]⁠[2]

This guide explains who created the standard, what the code contains, whether an invoice must carry it, how it differs from the cashless payment duty in shops, and what to watch so that the payment arrives in the right amount and is easy to match.

What PAY by square is

The standard was developed by the Slovak Banking Association with the banks and the company Forsys for the automated processing of payment orders from documents of any kind. The association publishes the specifications free of charge, and anyone may use them, without territorial or subject limits and without a fee.^⁠[1]

A code created according to the specifications carries the PAY by square logo so that nobody confuses it with another QR code. A code that does not follow the specifications must not carry the mark.^⁠[1]

Technically, the payment data are ordered, a CRC32 checksum is added, the result is compressed with the LZMA algorithm, converted to characters and encoded into a QR code. The current version 1.2.0 of the specifications, of 9 October 2025, made the beneficiary name mandatory.^⁠[2]

What the QR code contains

For a payment order the code carries mainly these details:^⁠[2]

• one or more bank accounts in IBAN and BIC format; the first one is the default, and a simple payment order can carry up to six,
• the amount and the currency under ISO 4217; the amount may be left out, for example for a donation,
• the due date,
• the variable, specific and constant symbol, or the SEPA originator’s reference instead,
• a note for the payee,
• the payee’s name and, optionally, address.

Besides a one-off order, the code can carry a standing order or a direct debit. The specifications recommend pre-filling the payment note so that the payer does not have to type one.^⁠[2]

Is the QR code on an invoice mandatory?

No. The VAT Act lists the mandatory details of an invoice, and a payment QR code is not among them. It is a service to the customer: they pay faster and without retyping the account number.^⁠[3] The mandatory details are summed up in Invoice requirements in Slovakia 2026.

How to use the QR code on an invoice well

• The right amount. The code should hold the amount the client still has to pay; for a partly paid invoice only the balance, otherwise they pay twice.
• The variable symbol. Choose it so that you can match the payment to the invoice on your statement; usually it is the invoice number.
• The due date. The date in the code should match the due date on the invoice, otherwise it confuses the client.
• The right account. If the code lists several accounts, the first one is the default.^⁠[2]
• The mark. The PAY by square logo or caption should appear under or next to the code.^⁠[1]

If the client does not pay even with a QR code, see Unpaid invoice in Slovakia.

How the client pays with the QR code

1. They open their banking app and choose to pay by scanning a QR code.
2. They scan the code from the PDF on screen or from the printed invoice; reading the invoice on a computer, they scan it with the phone straight from the monitor.
3. They check the pre-filled order: the payee, the account, the amount, the variable symbol and the date.
4. They confirm the payment like any other.

The variable symbol from the code travels with the payment into your bank statement, so even with several payments at once you know which invoice has been paid.

Checklist

• The code carries the PAY by square caption or logo.
• The amount in the code is the amount still to be paid.
• The variable symbol matches the invoice number.
• The default account in the code is the one you want to be paid to.
• You have test-scanned the code once with your own banking app.

QR payment in vporiadku

vporiadku prints a PAY by square QR code on invoices in euros on every plan, including the free Start plan. All you need is a bank account on your company profile and the QR code switched on in the company settings.

The code holds the account from the invoice (with your other accounts in the same currency as alternatives), the amount still to be paid, the due date, the variable symbol (the invoice number unless you enter another) and your company name; the caption PAY by square sits under the code.

On the Profi plan you upload your bank statement (camt.053, MT940 or CSV) to vporiadku, and it suggests which payment belongs to which invoice, helped precisely by the variable symbol.

For a QR code without an invoice, use the free PAY by square generator. You can try invoicing with a QR code for free; how to issue your first invoice is explained in How to issue an invoice in Slovakia.