What is an Online Cash Register?
An online cash register is an electronic device connected to the system of the Hungarian National Tax and Customs Administration (NAV), which regularly transmits transaction data to the tax authority via a mobile internet connection. Its purpose is to support tax audits through real-time or near-real-time data communication, reduce tax evasion, and enhance transparency in the economy.
The system became gradually mandatory in Hungary from 2013 onward for specific sectors, including retail, hospitality, and other service-based industries.
How does an online cash register work?
The device logs all cash register events and transactions and sends this information to NAV’s central servers at set intervals. Communication takes place via a mobile data connection (through a SIM card), meaning constant internet access is required.
The core component of the system is the Tax Control Unit (AEE), which:
- Is a secure, tamper-proof data storage module,
- Includes the mobile communication hardware,
- Operates independently from the rest of the cash register, ensuring data authenticity.
What kind of data is sent to NAV?
The online cash register transmits the following types of data:
- Receipt issuance details (time, amount, VAT breakdown),
- Cash register opening and closing events,
- Daily sales summaries,
- Technical events (e.g. error messages, restarts),
- Extracts of system logs.
NAV’s central system receives and analyzes this data in real time, making it easier to detect irregularities and conduct audits efficiently.
What is the Tax Control Unit (AEE)?
The AEE is the most critical component from both a technical and regulatory standpoint. Its functions include:
- Continuous logging of register events,
- Secure data transmission to NAV,
- Tamper protection — only tax authorities or authorized service providers can access it,
- Mobile internet communication via an embedded or external SIM module.
The AEE ensures NAV receives all relevant information from the cash register, regardless of the merchant’s intent.
What regulations apply to online cash registers?
The system is regulated by Decree No. 48/2013 (XI. 15.) of the Ministry for National Economy (NGM), which defines:
- The technical requirements for cash registers,
- The approval and certification procedures,
- Conditions for distribution and servicing,
- Obligations for users, including data reporting and audit access.
Only NAV-approved devices may be used, and servicing or software updates must be carried out exclusively by registered service providers.
Who is required to use an online cash register?
The use of an online cash register is mandatory for businesses that issue receipts (not invoices) as part of their operations and whose activity is listed in the official NAV sector list. This includes:
- Retail shops,
- Hospitality businesses,
- Hairdressers and beauty salons,
- Taxi services,
- Tradespeople offering repair or maintenance services.
NAV updates the list of applicable activities regularly.
Benefits for the tax authority and businesses
For NAV:
- Fast and automated data collection,
- Real-time control and monitoring,
- Quick detection of fraud and noncompliance,
- More targeted audits.
For businesses:
- Automated data reporting reduces administrative burden,
- Fewer errors and lower risk of penalties,
- Easier and faster receipt issuance.
Summary
The online cash register is one of the key tools in Hungary’s digital tax infrastructure. It transmits cash register events and receipt data in real time to NAV’s central servers. Its core is the Tax Control Unit (AEE), which ensures secure storage and mobile data communication. The system is mandatory for many types of businesses and plays a vital role in reducing tax evasion and increasing economic transparency.
Official definition
An online cash register is a device connected to the NAV system that transmits data at regular intervals via mobile internet to the tax authority’s central server. Its core component is the Tax Control Unit (AEE), which serves as a secure data storage and transmission module.
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