NAV Online Invoice and E-Invoicing: What You Need to Know in 2026

Many new sole traders think that invoicing simply means issuing the invoice and sending it to the client. In reality, there's another, less visible step: data reporting to NAV's (the Hungarian Tax Authority's) Online Invoice system.

What Is NAV Online Invoice Data Reporting?

NAV Online Invoice (NAV Online Számla) is a system to which real-time data must be reported for every invoice issued between domestic taxpayers — regardless of the invoice amount. This obligation applies no matter which tax form you've chosen (flat-rate tax, KATA, VSZJA).

Important: this doesn't mean the data sent to NAV is the invoice itself — you still have to issue the invoice and deliver it to your partner yourself; the data reporting is a parallel, technical obligation.

How Is the Data Reporting Fulfilled?

With online invoicing software (e.g. Billingo, Számlázz.hu) — the service automatically sends the data to NAV at the same time as the invoice is issued, with no extra work required from you.
With manual invoicing (paper-based or otherwise non-online) — you have to fulfill the data reporting manually, on the NAV Online Invoice interface, within a set deadline. This means significantly more administration, and a higher risk of human error.

Why Is It Worth Using Online Invoicing Software?

Automatic data reporting — you don't need to worry separately about reporting to NAV for every single invoice.
Fewer chances for error — manual data entry can easily introduce typos, which can later cause reconciliation problems.
Simpler bookkeeping — if your invoicing software syncs with your bookkeeping/financial system (e.g. Penzum), your revenue data stays automatically up to date, with no need to record it separately.

What Happens If Data Reporting Is Missed?

Incomplete or missing data reporting can result in a default penalty. The exact sanctions and deadlines are set out in NAV's current guidance — if you use manual invoicing, it's worth checking these regularly, so you don't face consequences later because of a forgotten report.

What to Watch For

Use online invoicing software if you can — this is the simplest way to make sure the data reporting obligation is fulfilled automatically.
If you use manual invoicing, keep accurate records of reporting deadlines — don't rely on memory.
Regularly check that your invoicing software and NAV's data are in sync — even in the case of a technical error, you're still responsible for correct data reporting.

Penzum Helps

Penzum can be connected to Billingo and Számlázz.hu, and also syncs directly with NAV Online Invoice data — so your revenue data updates automatically, without manual entry, and you don't need to worry separately about the technical details of data reporting.

Not using online invoicing software yet? We summarize how to get started in the Penzum Help Center. (exact link pending verification and insertion)