You can now purchase a new tank starter pack,

that gives immidiate access to the Ground Forces Closed Beta, as well as:

Light reconnaissance tank SdKfz 140/1 Aufklarungspanzer 38(t), based on the Pz 38(t) tank;
T-26 Light tank (construction bureau of factory #174) mod. 1939, up-armored, upg. in 1941;
Premium account for two weeks;
2000 Golden Eagles

http://online.gaijinent.com/story.php?title=War-Thunder_SdKfz-140%2F1-T-26E_Starter-Pack#_ga=1.185786666.284352515.1375216163

Golden Eagles and premium time will be activated immediately after your purchase; premium tanks will be available after the transition of the Ground Forces into the OBT stage.

The “SdKfz 140/1 and T-26E - Starter Pack” will be available even after the Ground Forces go into OBT.