You should know that the registration number is a unique identifier assigned by the tax office that permanently links a specific cash register to your company. You can find it in the service book, on the cash register casing (if it has already been applied), or in the CRK system for online cash registers. Remember – failure to permanently mark the cash register with this number on its casing risks financial penalties.
What exactly is the cash register registration number?
It is a unique sequence of digits (often containing the year of registration, e.g., 2025/000123456) assigned by the tax office upon registering the device. This applies equally to online cash registers and online fiscal printers. This number is permanent – assigned to the equipment for its entire period of use, regardless of whether you change your company's location in the future. Note that cash register record-keeping is an official registration process after which the device is officially approved for legal sales recording.
Where to look for the registration number?
If you use a modern online device, you should check the following places:
the service book – you will find the number next to the inspection and fiscalisation details,
a service report or module status report,
the device casing – if you have already fulfilled the obligation to apply it permanently.
If you are still using older cash registers (with paper or electronic copy), you should know that the tax office sent this number by post. Have you lost the official letter? You should contact your tax office as soon as possible to recover the data.
Important note: do not look for the registration number on the customer receipt. Only the unique number is located there, and receipt printouts themselves are used to keep a register of cash register errors and corrections, which allows documenting changes in sales records.
Your obligation – how to properly mark the cash register and avoid penalties?
The regulations here are strict. According to the regulation of the Minister of Finance of 25 June 2025 (§ 9, sec. 1, item 5), it is your obligation to enter the number in the cash register book and permanently apply it to the device casing. The number for the book and the cash register must be 100% identical and under no circumstances can it be assigned to other equipment.
Mark the device with an indelible marker, engrave a nameplate, or affix an abrasion-resistant sticker in a clearly visible place. Neglecting this duty is a direct route to receiving a financial penalty during a tax office audit.
Where does the device get this number from?
Your competent tax office is responsible for assigning the number. In online cash registers, this process is fully automatic. After completing fiscalisation, the cash register connects to the Central Repository of Cash Registers (CRK) – a specialised ICT system maintained by the Head of the National Revenue Administration – and downloads its number from it.
Quick facts you should know:
Registration number vs. serial number – these are two completely different identifiers. The serial number is assigned by the device manufacturer to identify the equipment itself, while the registration number is assigned by the tax office for tax record-keeping purposes.
Changing the registration number – as a rule, this is impossible. The only exception is re-fiscalisation after replacing the device's memory module.
Leave formalities to the experts
Worried about errors in official procedures? By choosing equipment on Fiskasy.pl, you can be sure that our specialists will handle the entire process of properly marking the cash register for you in accordance with strict regulations. Contact us and work with your cash register without the risk of penalties.