20 CFR §418.2125

1. (a)If you must pay an income-related monthly adjustment amount, your total Medicare prescription drug coverage premium will be the sum of:
   1. (1)Your prescription drug coverage monthly premium, as determined by your plan; plus
   2. (2)Any applicable increase in the prescription drug coverage monthly premium as described in 42 CFR 423.286; plus
   3. (3)Your income-related monthly adjustment amount.
2. (b)Regardless of the method you use to pay your Medicare prescription drug coverage premiums to your Medicare prescription drug coverage plan, you will pay any income-related monthly adjustment amount you owe using the method described in 418.2112.