T-Mobile has released software update G920TUVU5EQC2 for Galaxy S6 and G925TUVU5EQC2 for Galaxy S6 Edge in the US. The update also includes March Security Update.
The new Android March security patch brings fixes for Vulnerabilities and Exposures in the Android OS. The new update also includes bug fixes and other performance enhancements for the Android device.
The new security patch update G920TUVU5EQC2 for Galaxy S6 and G925TUVU5EQC2 for Galaxy S6 Edge will roll out over OTA with 100MB size. However, you can also check it manually by heading to Settings » About Device » Download Updates Manually.