In general, if you have selected automatic Social Security benefit deduction, you do not need to separately pay your monthly Medicare drug plan premiums while waiting for the automatic premium deductions to start.
When your Medicare plan premium payment request is processed by the Social Security Administration (SSA), you will find that the unpaid monthly premiums you owe to your Medicare plan will be withheld from your next Social Security benefit all at one time.
For example, if you enroll in a plan in December, January would be your first SSA premium deduction, however it may take SSA a month to process your request. So, in this example, no payment would be deducted in January and two premium payments would be deducted in February. If your SSA benefit check cannot cover the two premium payments, you will be billed for the difference.
To minimize the burden of multiple payments being deducted at one time, some Medicare plans will send you a Coupon Book to make your monthly premium payments before your Social Security check deductions begin. You can contact your Medicare plan's Member Services department for more details and information - the toll-free number for Member Services is printed most plan materials and on your Member ID card.
(general source: U.S. Department of Health & Human Services)
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