MMC Benefits Handbook
If You Take a Leave of Absence
Because the fixed Company credits are conditioned on your eligible base pay, they will be suspended when you take an unpaid leave of absence (including long term disability).
Upon your return, fixed Company credits will resume (to the extent you remain eligible for them), and there will be no retroactive fixed Company credits for the period of your leave.
If you take a paid leave of absence, fixed Company credits will continue during the leave.