It depends on the specific plan area. A carrier they offered in one area and not another. It is really not a rebate it's a Part B reduction.
For instance in our state and specific counties Humana is offering a $40 Part B give back. What that means is a person that would normally pay $134 a month for their Part B premium what get a rebate back on their social security check of that $40 us and that paying $94 for their Part B premium. They can sometimes take up to 3 months before that I get back to kick in.
You see a lot of the $40 part B premium reduction nationwide on MA only plans. Humana has that option in a large number of states. Part B premium reduction plans in FL are all over the state now, you used to see the them in primarily around Miami & also around Tampa. They give these premium reductions because the they get so much from the government. I had a company rep tell me years ago that the reimbursement rate on a Midwest MAPD may be about $800 per month, vs. some of the FL counties were getting $1800 per month. MAPD gets money from CMS based on what they spend on average per Medicare beneficiary in a county. I would like to see some actual reimbursement numbers per county & state, I have looked for them but have not able to find it.