Posting workers from Bulgaria to another EU country: the A1 certificate and its limits

The A1 certificate proves that a worker posted from Bulgaria to another EU country stays insured in the Bulgarian system under Regulation (EC) No 883/2004. It is issued by the National Social Security Institute. It does not settle pay: under Directive 96/71/EC, as recast by Directive (EU) 2018/957, a posted worker receives the conditions of the host country.

How the A1 is obtained, and how long it takes

The employer files a notification on form OKd-236 with the competent regional directorate of the National Social Security Institute, together with a copy of the posting order. The institute decides within 30 days of receiving the request. That period runs from a complete request, so a missing annex to the posting order does not extend the clock, it restarts it.

The A1 is issued before work in the host country begins. Inspectors there check this certificate specifically, and a site without one is treated as undeclared work by the host state, even where contributions are being paid correctly in Bulgaria. The institute charges no fee for the certificate, but the cost is in time: 30 days before mobilisation, not after it.

Separately from the A1, most host states require their own prior declaration of the posting in a national system, filed before the first working day. That is a second procedure before a different authority and is not covered by the Bulgarian certificate.

The 24 month limit, and what stays in Bulgaria

Under Regulation 883/2004 a posting on this basis runs for up to 24 months. After that there has to be a break before a new certificate is issued for the same worker and the same country. The scheme is not an instrument for permanent presence on a foreign market. A project planned over three years is not covered by a run of A1 certificates and needs another form of presence in the host state.

The 24 month ceiling belongs to Article 12 of Regulation 883/2004, which is the posting rule. A worker who normally pursues activity in two or more member states falls under Article 13 instead. The A1 issued on that basis follows the registered office of the employer and the share of work performed in the country of residence, it carries no 24 month ceiling, and it is the correct basis for a fitter who rotates between sites in Germany and Austria all year. Filing a posting certificate for that pattern is the error a host inspectorate finds first.

The same article carries two conditions that are tested before the duration is. Under Article 14(2) of Regulation (EC) No 987/2009 the employer must normally carry out substantial activities in Bulgaria, not purely internal administration, and a company registered in Sofia with no turnover on the Bulgarian market does not satisfy that by holding the registration alone. Article 12(1) of Regulation 883/2004 adds that a posted worker may not be sent to replace another posted worker. Rotating three people through one position for 24 months each therefore does not stretch the scheme to 72 months. Both conditions are examined by the host inspectorate, and a certificate issued on facts that do not hold can be withdrawn by the institute after the work is already done.

What stays in Bulgaria: social security contributions, health insurance and the employment relationship. What moves to the host state: pay and working conditions.

Pay: what the 2018 recast changed

The original text of Directive 96/71/EC obliged the employer to apply the minimum rates of pay of the host state. Directive (EU) 2018/957 changed that to remuneration in the host state, meaning every mandatory element of pay there, including those set by generally applicable collective agreements. In sectors such as construction in Germany, Austria and the Netherlands, that is the difference between the national minimum and the sectoral rate, which is often considerably higher.

This is where the corridor typically breaks. The employer prices a project on Bulgarian labour cost, adds the gap up to the host country minimum wage, and treats that as sufficient. An inspector on site finds that the applicable collective agreement sets a higher rate for the relevant skill group, orders back payment and imposes a fine. The project margin disappears at the first inspection, not at the end of the contract.

A separate question is the posting of a third country worker employed in Bulgaria. The Bulgarian work authorisation stays in place, but the host state decides on its own whether to admit that worker to its site, so the check runs in both directions. The grounds for the Bulgarian authorisation are set out in the single permit procedure for employers, and the contribution side stays with the rules in social and health insurance for third country workers.

A posting is costed on three figures: 30 days for the institute to decide, 24 months as the ceiling under the regulation, and the actual sectoral rate in the host state. Country by country timings are compared in the permit timeline by country. To work through a specific site, see the employers page.