- Margin
- Market Value
- Marriage
- Married Filing Jointly
- Married Filing Separately
- Material Participation
- Medical Expenses
- Medical Savings Account (MSA)
- Medicare Part A
- Medicare Part B
- Medicare Tips
- Medicare Wages
- Midpoint Class Life
- Modified Accelerated Cost Recovery System (MACRS)
- Modified AGI (MAGI)
- Mortgage Interest Credit
- Moving Expenses
- Multiple Support Agreement