Turning 65 in December. Since I retired 4 years ago my AGI has been around $425,000 annually due to about $325,000 in annual contractual deferred income payments (the rest due to dividends, interest, capital gains). This suggested I will pay $318.10 in "extra" Part B and $70 in "extra" Part D monthly premiums for the next few years for my wife and me if based upon 2018, 2019 or 2020 1040s. The amount of these contractual deferred income payments will fall to $25,000 so my AGI should be around $125,000 in 2021. Not taking SS until age 70. What is the likelihood of a favorable IRMAA appeal based upon lower future deferred income payments which I could prove? The wild card is div, interest, capital gains.