This question is pretty complicated. Sallie Mae serviced federal student loans back in 2006, but they also issued private student loans. Navient later took over as a federal student loan servicer, and they did also handle some federal direct consolidation, which could mean the debt is federal. However, Navient also advertises personal loans on their site, which would mean that debt cannot be converted to federal. In other words, the Sallie Mae to Navient timeline really doesn’t shed much light.

The best strategy here is to figure out whether or not your loans exist in the federal student loan database. The links in the article above should explain the process.