You must have a certified assessment method authorized by the TMMi Foundation. The assessment method can be developed by yourself based on TAMAR (TMMi Asssessment Method Application Requirements), or the one is authorized by other organizations (that is, use the assessment methods of other organizations that already have been certified by TMMi).
The assessor must use a certified assessment method.
The assessor must meet the qualification criteria defined by the assessors and the lead assessors.