Posting Employees Into Serbia: Social Security Totalization Agreements and the Equivalent of an A1 Certificate

An employer in Romania sending a specialist to a Serbian subsidiary, a client site, or a project team for several months is making the same kind of decision an EU-to-EU posting involves: where does this person's social security coverage sit for the duration of the assignment. The mechanics differ, though, because Serbia is not an EU member state, so the EU's A1 certificate and Regulation 883/2004 framework do not apply directly. Instead, whether a posted worker can remain under their home country's social insurance system depends on whether that home country has a bilateral social security agreement with Serbia, and what that specific agreement says.

Why this isn't automatic

Without an applicable bilateral agreement, the default rule is territorial: a person working in Serbia is, in principle, subject to Serbian social security law for the period they work there, regardless of where their employer is based. A bilateral agreement is what creates an exception to that default, allowing a worker who is only temporarily posted to remain under their sending country's system instead, provided the posting meets that agreement's conditions.

Serbia has built out a substantial network of these agreements over time, covering many of its largest sources of inbound and outbound labour mobility. Romania is among the countries with an agreement in force, alongside others including Belgium, Cyprus, Turkey, Australia, Canada, and China, each negotiated and signed separately and each with its own detail on scope and duration.

What the Serbia-Romania agreement covers

The Serbia-Romania social security agreement, signed in Belgrade and in force since the following year, covers a broad range of benefits: old-age and invalidity pensions, medical and maternity benefits, work accidents and occupational diseases, and, specifically on the Romanian side, temporary incapacity indemnities, the death grant, and the state child allowance.

Its posting rules sit in a dedicated article covering employees sent abroad by their employer. An employee posted from one country to the other remains under the sending country's law for the duration of the posting, provided the assignment is expected to last no more than 24 months. Self-employed individuals working temporarily in the other country are treated the same way, with the same 24-month ceiling.

Where an assignment runs longer than originally planned, the agreement allows an extension of up to a further 24 months, but only with the other state's agreement, and the request for that extension has to be made before the initial 24-month period actually expires. Either the employee and employer jointly, or a self-employed person individually, can make this request. The agreement also addresses a handful of narrower categories separately, including international transport staff, ship crews, harbour workers, and public servants posted abroad, each with its own treatment, and it leaves room for the two countries' authorities to agree exemptions in individual cases beyond what the standard rules cover.

For pension purposes specifically, periods of insurance completed under each country's own system are generally used to calculate benefits under that country's law, with provisions allowing periods from the other state, and in some cases from certain third states, to be counted toward eligibility where a person's career has spanned more than one system. Where a benefit becomes payable only once periods from both states are combined, the agreement sets out a pro-rata method for apportioning it.

The certificate itself

The agreement's text does not spell out a specific certificate form in the way EU Regulation 883/2004 does with the A1. What it does establish is the administrative architecture behind one: the agreement designates competent authorities in each country, defines what counts as a competent institution for different benefit categories, and refers to a separate administrative arrangement between those authorities that sets out the practical procedures, including, in practice, how a posting is documented and confirmed to the host country's institutions. In Serbia, this runs through the Republic Fund for Pension and Disability Insurance, the PIO Fund, which administers the agreement's day-to-day application on the Serbian side.

In practice, this means an employer posting a worker from Romania to Serbia under this agreement should expect to apply, before the assignment begins, for a certificate of coverage through the competent institution in the sending country, the same starting point as an A1 application within the EU, even though the certificate itself sits under a different legal instrument and is confirmed through the bilateral agreement's own administrative channel rather than an EU regulation.

What employers should confirm before a posting starts

Because each of Serbia's bilateral agreements is negotiated separately, the posting rules, duration limits, and extension procedures are not identical across them. An employer that has previously posted workers to Serbia under, say, the Belgium or Cyprus agreement should not assume the Romania agreement's 24-month cap and extension process apply the same way to every corridor. Before relying on any agreement to keep a posted employee under home-country coverage, employers should confirm:

• Whether a social security agreement between the sending country and Serbia is actually in force, since not every country Serbia hires from has one
• The maximum posting duration the specific agreement allows before Serbian coverage would otherwise apply
• Whether an extension is available, and the deadline for requesting it before the initial period runs out
• Which institution in the sending country issues the certificate of coverage, and what documentation that institution expects from the employer

Where no agreement exists between the sending country and Serbia, the posting falls back to the territorial default, meaning the worker and employer should expect Serbian social security obligations to apply from the start of the assignment, and should plan the cost and administrative impact of that accordingly rather than assuming reciprocity that isn't there.

How Nestlers Group supports employers on cross-border postings into Serbia

Nestlers Group's tax team manages the certificate-of-coverage application and tax assessment on posting contracts for employers sending staff into Serbia, confirming at the outset whether a bilateral social security agreement applies to the specific sending country and structuring the assignment's documentation around that agreement's actual terms rather than general EU posting assumptions. Our Global Mobility service coordinates this alongside the Serbian immigration side of the assignment, so the social security and work-authorization tracks move on the same timeline, and our Consultancy tiers are available where a posting's duration or structure raises questions that go beyond a standard short-term assignment.

Sources: Republic Fund for Pension and Disability Insurance of Serbia (PIO Fund), text of the Agreement on Social Security between the Republic of Serbia and Romania, signed in Belgrade, 28 October 2016; PIO Fund, list of Serbia's bilateral social security agreements in force.