The electronic invoicing system (SEF) sounds like something that concerns only large companies and PDV payers, but flat-rate entrepreneurs run into it more and more often. If you ever issue an invoice to a government institution or to a business that requires it, SEF becomes part of your story too. In this article we explain who is required to use it, what it means to be a voluntary user, and which obligations arise once you enter the system.

What SEF is and who is required to use it

SEF is a state platform (efaktura.gov.rs) through which electronic invoices are issued, sent and received. The Law on Electronic Invoicing distinguishes two groups of users: those who are required to use it and voluntary users. The required users are public and private sector entities, primarily those who are in the PDV system. A typical flat-rate entrepreneur is not in PDV, so as a rule they are not automatically required to use SEF.

This means that a flat-rate entrepreneur who works exclusively with private companies outside the PDV system and with individuals generally has no obligation to use SEF. The situation changes the moment the public sector appears, or a partner who insists on an electronic invoice.

When a flat-rate entrepreneur must use SEF (B2G)

The most important trigger is doing business with the public sector (B2G). If you invoice a ministry, a public enterprise, a local government, a school or any public institution, an electronic invoice is mandatory, even if you are not in PDV. In that situation the flat-rate entrepreneur must register on SEF and issue an e-invoice before submitting a payment request to the public sector entity.

In other words, registration is formally „voluntary”, but in practice mandatory if you want to get paid for work done for the state. Without an e-invoice issued through SEF, the public client cannot pay your invoice.

Voluntary user: what it entails

As soon as a flat-rate entrepreneur registers on SEF and issues their first invoice, they become a voluntary user of the system. This status is not a harmless one-off move, because it carries an obligation to remain in the system. Under the Law on Electronic Invoicing, a voluntary user is required to use SEF in the current and the following calendar year.

Anyone who registered during 2024 can deregister at the earliest from 1 January 2026.
Anyone who registers during 2025 can deregister at the earliest from 1 January 2027.

That is why it is important not to treat registration as a momentary formality for a single job with the state, but as an obligation that follows you at least until the end of the following year.

Issuing and receiving invoices

Once you enter the system as a voluntary user, the obligations run in both directions. In short, here is what it looks like in practice:

Public sector (B2G): an e-invoice is mandatory; you issue it through SEF before the payment request.
Private sector (B2B): a voluntary user issues and receives invoices through SEF in transactions with private sector entities as well.
Receiving: as a voluntary user you are required to receive e-invoices through SEF from any sender.

The practical point: if you are a voluntary user, you cannot choose to receive only the „nice” invoices. The system becomes your official channel, so you need to check it regularly so that an incoming document does not slip past you.

How to register and deregister

To access SEF you need a qualified electronic certificate and an account on eID.gov.rs, after which you log in to the efaktura.gov.rs portal. When registering, flat-rate entrepreneurs most often choose the „Other” type (rather than „Entrepreneur”), because they are not PDV payers. It is best to check the details regarding the PDV category and the basis code with your bookkeeper to avoid errors when setting up the account.

Deregistration is only possible once the mandatory period expires (the current year plus the following year). A request for removal is submitted to the Central Information Intermediary by email at cip@mfin.gov.rs, together with the name of the entity, the PIB, and the basis for deregistration. The data remains archived in the system; only the user’s status changes.

Key takeaways

A flat-rate entrepreneur outside PDV is, as a rule, not automatically required to use SEF.
Doing business with the public sector (B2G) requires an e-invoice and registration on SEF.
With your first issued invoice you become a voluntary user.
The mandatory duration is the current plus the following calendar year; deregistration goes to cip@mfin.gov.rs.
As a voluntary user you are required to both issue and receive invoices through SEF.

Before you register on SEF just for the sake of a single job, consider the obligation that lasts at least until the end of the following year. If you need help with registration, issuing or deregistration, get in touch with us.