Social security contributions dispute: Court rules on declaratory nature of cross-border insurance rules and interest start date.

The Supreme Court dismissed the cassation appeal regarding the return of social security contributions for workers sent to Germany, upholding the lower court's decision. The court found that Polish law applied to the workers in question and that the Social Insurance Institution's refusal to certify this application was legally flawed. However, the court ruled that interest on the returned contributions could only begin accruing from the date the employer filed the request for their return, not from the date the contributions were deemed unpaid.