Lowering Medicare Premiums and Prescription Drug Costs Act This bill transfers certain programs that provide Medicare premium and cost-sharing assistance for low-income individuals from Medicaid to Medicare. Specifically, the bill establishes a program under Medicare to assist low-income Medicare beneficiaries with premiums, coinsurance, deductibles, and other costs. Currently, such assistance is provided through Medicare Savings Programs, which are administered by state Medicaid programs. The bill also establishes a related special enrollment period under Medicare, expands eligibility for assistance to beneficiaries with income up to 200% of the federal poverty line, and provides for joint eligibility determinations with respect to the bill's program and the low-income subsidy program under the Medicare prescription drug benefit.