Can I return some IRA distribution after taking it

[SLYKTAX]

I am 75 and I got a windfall this year as I got a year of backpay for my SS spousal support that will raise my Medicare Premium Part B in 2027 because of IRMAA. 

Look like my 2025 Magi will just past the standard IRMAA threshold, I figured out it would be better to convert some $40-50K of my IRA money to my ROTH and stay within the 1st level of IRMAA .   

The trouble is it is difficult to figure out now how much my 2025 MAGI will be until the middle of Feb 2026 when all tax papers are due. 

Assuming  I convert too much, say $50K already. And that bump me to 2nd IRMAA level,  can I return $10K so as to keep me in the 1st  IRMAA level?

[Bsch4477]

Once you convert from an IRA to a Roth you can’t take it back. You also can’t return or contribute a RMD to a retirement fund. 

[VolvoGirl]

And you have to take your RMD out before you convert any to a ROTH.   Did you already take your 2025 RMD?  Before you made any conversions to ROTH?  

[SLYKTAX]

I knew I have to take the RMD before doing a ROTH conversion.  I did that early this year for fear that the value on my retirement account may loss value towards the end of the year. Thanks