How Close Were The Irmaa Income Bracket Projections?

I project Medicare IRMAA income brackets in Medicare IRMAA Premium MAGI Brackets. Because IRMAA uses a two-year lookback, we can’t calculate this year’s exact income thresholds against the IRMAA brackets two years out. The inflation data required to calculate them are simply not available.

At best, we will have three monthly CPI data points by mid-December out of the 12 needed to calculate the IRMAA brackets. I can only fill the missing nine data points with estimates. I’m not an economist. I’m not trying to predict future inflation based on economic indicators. I fill the empty slots with only mathematical extrapolation.

I use two sets of numbers: a lower set with 0% inflation for conservative projections and another set with some inflation for likely projections. A reader asked how close my past projections were to the actual brackets published the following year.

That’s a good question, but honestly, I haven’t tracked them until now. I went back and recalculated my projections using the same methodology but with only data available at the time.

I’m listing the numbers for only married filing jointly to keep it simple. The single brackets are exactly half of these numbers, except for the 3.2x bracket. The 3.2x brackets were fixed during these years.

* I haven’t seen the official 2027 numbers. All necessary data points are published, but it’s still unclear how the government will handle the missing CPI number for October 2025 when they didn’t collect price data during a shutdown. The actual column for 2027 uses my latest projections.

We had positive inflation in all previous five years. The 0% inflation projections were lower than the actuals, by design. The “some inflation” projections (currently using 3%) either matched or were slightly below the actual brackets. If you had used the higher set of projections, you’d be OK, but you were cutting it close unless you added a buffer below those numbers yourself.

Most people use the 0% inflation projections to be more conservative. I show the higher projections only to indicate how much headroom you potentially have, which is usually small ($2,000 or $4,000 for married filing jointly, $1,000 or $2,000 for singles).

I would go with the lower 0% inflation projections because the risk/reward tradeoff is lopsided. It’s not worth wringing out the last drop. See Use Pascal’s Wager When You’re Not Sure About Tax Rules for my general principle in dealing with uncertainty.

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