Prosecutors' evidence is based, among other things, on telephone calls and contacts via the Internet.
The group is also said to have planned attacks against migrant groups and mosques.
A regular coup d'état with an attack on members of parliament was also discussed, according to the prosecutor's side.
None of the planned attacks were carried out, and prosecutors have therefore lowered the penalty requirements.
The remaining charge is conspiracy to carry out a terrorist attack, which can lead to ten years in prison.
The defendants are between the ages of 26 and 66.
The likely leader is a previously known militant right-wing extremist in his 60s, residing in the Alpine region
The trial is expected to be completed on February 3.