Material duties - In LTD plans, the basic and essential requirements of a job. To be considered disabled, employees must be unable to perform material duties, not incidental or insignificant tasks.

Maximum benefit - For disability benefits, the maximum dollar amount an insured will receive while disabled. For health benefits, the total dollar amount the insurer will pay on any given individual.

Maximum benefit duration - The longest period for which employer-sponsored disability benefits will be paid, provided that the employee remains continuously disabled. Typically, the lesser of the number of years until Social Security normal retirement age or the age specified in the plan.

Maximum monthly benefit - The highest dollar amount that an employee who has been disabled will receive each month from the employer's LTD plan.

Maximum medical improvement (MMI) - Maximum medical improvement (MMI) - The point at which an employee who has been disabled reaches a plateau in recovery, so that any remaining impairment is considered to be permanent. In workers' compensation, MMI triggers the transition from temporary to permanent Disability benefits.

Medical necessity - Services/procedures which are approved in accordance with recognized medical standards as effective and appropriate and are essential to retard, reduce or eliminate an impairment.

Medical only - A type of workers' compensation claim that involves no wage replacement (because no work time was lost) but only reimbursement of medical expenses.

Medical record - A written or electronic account of a patient's medical history, current illness, diagnosis, details of treatments, chronological progress notes, and discharge recommendations. This is a legal document the patient is entitled to read and is authenticated by the physician's signature. There are strict rules regarding the confidentiality of the medical record.

Medicare - Federally administered health insurance plan intended primarily for person age 65 and older; also available to individuals with disabilities after they have received Social Security Disability Insurance benefits for 24 months. Medicare has two parts, part A covers hospital costs; part B covers medical expenses.

Mental illness - A psychiatric or psychological condition regardless of cause such as schizophrenia, depression, manic depressive or bipolar illness, anxiety, personality disorders and/or adjustment disorders or other conditions. These conditions are usually treated by a mental health provider or other qualified provider using psychotherapy, psychotropic drugs, or other similar methods of treatment.

Mental illness limitation - Limit on the period of time (often 24 months) over which LTD benefits will be paid when an employee is disabled as a result of mental, emotional, or nervous condition that is being treated on an outpatient basis. The limitation does not apply while the individual is confined to a hospital or institution.

Minimum monthly benefit - The lowest dollar amount an employee who has been disabled will receive each month from the employer's LTD plan. Some plans guarantee a minimum benefit, regardless of income received from other sources.

Monopolistic state fund - In certain states, a fund set up as an agency of a state government, from which all employers who are not self-insured or covered by group self-insurance are required to purchase workers' compensation insurance.

Morbidity - The expected incidence and severity of illness and accidents in a specified group.