You automatically qualify for Extra Help if you have Medicare and meet one of these conditions:
You have full Medicaid coverage.
You get help from your state Medicaid program paying your
Part B premiums (belong to a Medicare Savings Program).
You get Supplemental Security Income (SSI) benefits.
Medicare will mail you a purple letter to let you know you automatically qualify for Extra Help. You don’t need to apply for Extra Help if you get this letter.
Keep the letter for your records.
If you aren’t already in a plan, you must join a Medicare drug plan to get this Extra Help.
If you don’t join a drug plan, Medicare may enroll you in one.
If Medicare enrolls you in a plan, Medicare will send you a yellow or green letter letting you know when your coverage begins.
Different plans cover different drugs. Check to see if the plan you are enrolled in covers the drugs you use and if you can go to the pharmacies you want. Compare with other plans in your area.
If you’re getting Extra Help, you can switch to another Medicare drug plan anytime. Your coverage will be effective the first day of the next month.
In most cases, you will pay only a small amount for each covered prescription.
If you have Medicaid, Medicare will provide you with prescription drug coverage instead of Medicaid. Medicaid may still cover some drugs that Medicare prescription drug coverage doesn’t cover. Medicaid may still cover other care that Medicare doesn’t cover.
If you have Medicaid and live in certain institutions (like a nursing home), you pay nothing for your covered prescription drugs.
If you qualify, your drug costs in 2010 will be no more than $2.50 for each generic drug and $6.30 for each brand‑name drug. Look on the Extra Help letters you get, or contact your plan to find out your exact costs.

Refer to this link for additional help: http://www.medicare.gov/Publications/Pubs/pdf/10050.pdf