Traditionally, there is no formal grading system involved in the art of Taiji Quan.
However, throughout the Chinese martial arts there are various levels of progression, depending on the level of the practitioner.
Student:
A student is the most common level of practitioner. He/she receives the basic level of instruction in his/her chosen martial style.
Disciple:
A disciple is a student who has been accepted as a dedicated practitioner by his/her master and has been chosen to receive indepth instruction in one or two specialty areas, for which he/she will be responsible for passing on to any students that he/she may take in future.
Lineage Disciple:
A lineage disciple is a disciple who has been chosen by his/her master to pass on the whole curriculum of his/her martial art in its entire form. He/she will receive the deepest level of instruction, and will be regarded as family to the master.