Q: Can a senior qualify for Medicaid if they already receive Medicare?
A: Yes, a person can receive both Medicare and Medicaid. When a Medicare beneficiary begins receiving Medicaid benefits they are deemed a "Dual Eligible." Dual eligibles have enhanced benefits.
Here's how it works: Medicare continues to be the person's primary insurer. They are free to go to any provider that accepts Medicare. This means they are not limited to "Medicaid Doctors" (as those who are not Medicare eligible typically are).
If the beneficiary has a Medicare supplement or is a member of an HMO or other Medicare Part C Advantage plan, that insurer will be the secondary insurer. In this case, Medicaid is now the "tertiary" insurer and picks up expenses that Medicare and the HMO do not.
Dual eligibles also have their Part B Medicare premium paid and their Part D prescription premium subsidized. Co-pays for prescriptions medicine go to $1 and $5 with no "donut hole." Medicaid may also provide long-term care services in addition to the above depending on the recipient's circumstances.
Unless Social Security determines that you are disabled, you are eligible for Medicare when you turn 65. Much of the premium has been paid if you have worked the requisite number of quarters and contributed to Social Security. As a Medicare beneficiary (or even if you are not) you may be eligible for Medicaid if you have limited income and resources.