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The company I work for uses Rosclar to process payroll for the employees who work in Spain. Unfortunately, the experience has not been great, and the entire Spanish team complains repeatedly about Rosclar in our regular check-ins with HR. Payroll payments are timeline; however, they opt to provide payslips through an online system. The payslips are consistently posted late, and the online system is (1) very error prone, (2) not user friendly and, very surprising for a company supporting Spanish employees, (3) not even available in Spanish!
When we need to contact Rosclar (as instructed to do so by HR), the responses are incomplete and not generally respectful. We raised a series of formal complaints in the organisation due to Rosclar employees responding with phrases like "It isn't my job to help you" (and this in response to a scenario where there were issues with their online platform and we could not access payslips).
In the case of medical leave, they gave the wrong information to our company HR about medical leave payroll, citing data that had been out of date for three years at that time.
We've raised on multiple occasions requests to have the provider changed. If you're a company looking for a payroll service in Spain, you might want to keep looking.