According to information from my October MMAP presentation, here are the income limits for the Medicare Savings programs. The amounts are for 2012, but still can be used as a general reference.
QMB (Qualified Medicare Beneficiary): monthly income limit is $930, assets of $2000 for single, $1260 income, $3000 assets for married. QMB pays for Medicare B premium, A&B co-pays and deductibles
SLMB (Specified Limited Medicare Beneficiary: single monthly income $931 to $1117; assets $6940. Married income $1261-1513, assets $10,410. SLMB pays for Medicare B premium
ALMB (Additional Low Income Medicare Beneficiary): single monthly income $1118-$1256, assets $6940. Married income $1514-1702, assets $10,410. ALMB pays for Mecidare Part B premium