Why migration data misses millions of workers?
Working Paper: "Workers at Your Service — Data on the Posting of Third-Country Workers from Poland"
This working paper looks at a group of workers who cross borders to work in another country, but are not considered - and therefore not counted - as migrants. These mobile workers remain part of their home labour market while working abroad, creating a double challenge for both migration and labour statistics. Welcome to the mysterious world of posted workers!
The paper was developed as part of the European Birds of Passage (E-BoP) project at the CNRS and will be presented at the Migration Policy Centre at the European University Institute (Florence, Italy) on 13 May 2026. You can register to attend the event online via the event page.
Most migration statistics track people who change their country of residence. But many workers cross borders without ever being counted as migrants. In the EU, posted workers move temporarily under their employer’s right to provide services — not as migrants. As a result, a large share of cross-border labour mobility remains invisible in migration statistics. In 2023 alone, 1.5 million people across 25 EU Member States were posted, on average 2.7 times, to provide services in another EU country.
This paper focuses on one part of this invisible workforce: third-country nationals (TCNs) posted from Poland to provide services in other EU Member States. Posting, established under the EU’s free movement of services, allows companies to temporarily send employees abroad and applies equally to TCNs legally residing in the EU. As a result, posted TCNs move across EU borders not through the free movement of labour, but through their employer’s right to provide services—creating a parallel channel of intra-EU mobility that can bypass standard work permit restrictions.
Despite their growing importance, posted TCNs remain largely invisible not only in conventional migration statistics but also in data sources on posted workers. To address this gap, the paper draws on several underused administrative data sources on social security affiliation, pension and disability insurance, driver certificates, and temporary work permits in Poland—Europe’s leading posting country and a major destination for temporary labour migrants. The findings show that TCNs posted from Poland are increasingly short-term labour migrants rather than Polish nationals or long-term residents, resulting in a form of “double” migration. This is particularly evident in the international road transport sector, where postings frequently last longer than the “temporary” periods assumed in EU legislation.
Posted TCNs have become essential to Poland’s international road transport sector, especially as labour shortages have intensified following Russia’s invasion of Ukraine. As migration from traditional source countries such as Ukraine has declined since 2022, workers from sub-Saharan Africa and Asia have increasingly filled the gap—often being posted directly to other EU countries.
These patterns suggest that Polish firms rely heavily on non-EU labour to sustain service exports within the EU, generating a form of sequential or “double” migration in which workers first migrate to Poland and are then posted onward to other Member States. In doing so, they reveal how temporary migration itself is being reconfigured into more complex and increasingly permanent systems of labour recruitment and mobility.
The full working paper is available below.
