Mathematics performance and socioeconomic status (SES) are positively related, but the reasons are not well understood. Moreover, the strength of the relationship in large-scale assessments like PISA differs between countries, for example, between Finland and Germany. In the PISA studies, mathematical word problems are used, which cover four mathematical content areas. In the present study, we reanalyzed data from PISA 2003 to 2018 to investigate whether word problems in these content areas were related differently to SES across the two countries. The results suggest that the relationship can be attributed to different content areas in both countries. This emphasizes the importance of considering item characteristics when addressing the relationship between SES and mathematical word problem solving