IRMAA: my income dropped; will they reduce IRMAA automatically or do I need to contact Medicare?

Hi, all; there is no SSA-44 form reason for my income dropping. I merely had a lower AGI and MAGI in 2024. It drops me down into the lowest IRMAA level.

Will they know this from my tax filing (1040)? Or do I have to call them/write them? The reasons my income dropped are not related to any of the usual 44 Form’s reasons. Is there a different form?

I phoned, but only sat on hold, and after an hour or so had to leave.

Thanks for any advice!