What is the ruling on selling a visa to a worker, then returning the money to him after a year for him to work at the institution?

It is not permissible to sell a visa because it is a sponsorship (kafalah), which is a gratuitous contract, not an exchange for consideration. The price of influence or status (thaman al-jah) is prohibited by many scholars. The price of the visa must be returned to the worker if it was taken from him without any مقابل (exchange/consideration) other than the sponsorship itself. However, if it was in return for expenses, effort, and services, then its return is not obligatory. There is no objection to the worker working for the sponsor.