I paid my first Medicare premium for June-Aug 2016 of $365.40 and just received my bill for Sep-Oct-Nov in the amount of $1096.20 (3 x my first quarterly payment).
It appears that they've billed my quarterly amount as monthly because even at the maximum income adjustment (over $28k/yr) the monthly payment estimate is only $352.60 ($38.40 less than what I'm being charged for 3 months $1057.80 vs my $1096.20).

How much should I pay/What should I do???

Hi,

I'm sorry, but I don't have a good answer. It certainly appears as though a mistake has been made, so I would try resolving it by phone. The billing notice should show a phone number to call if you have questions about your bill, so I would start there. Don't fail to pay at least your correct Medicare premiums timely, since that could result in cancellation of your coverage.

Best, Jerry