Valid reasons to perform a TMMi assessment include identifying areas that need improvement (2), determining which accomplishments have been made (3), and using the assessment as a basis to become formally TMMi certified (4). Assessing individual tester performance (1) is not a typical objective of TMMi assessments, which focus more on process maturity and improvement rather than individual performance evaluation.
Reference:
"TMMi assessments are used to identify improvement areas and assess progress against maturity goals, not individual performance".