"Beginning May 23, the Samsung Galaxy S 5 will have a software update to Android version 6.0.1/ Baseband G900T3UVU1GPE1 OR G900TUVU1GPE1 via Wi-Fi or Samsung Smart Switch for PC. This update provides new features."
Source: Software versions & updates: Samsung Galaxy S 5 | T-Mobile Support
Source: Software versions & updates: Samsung Galaxy S 5 | T-Mobile Support