Is this statement true and, if it is, could you provide a citation from the IRS.gov site: Taxes withheld from an RMD are deemed withheld equally throughout the year?

[dmertz · Accepted solution]

Yes, it's true unless you are able to show otherwise and choose to do so.  This clear from the way the calculations are performed on Part I of Form 2210 and is also explicitly stated in the instructions for line 19 of Form 2210:

https://www.irs.gov/pub/irs-pdf/f2210.pdf

https://www.irs.gov/pub/irs-pdf/i2210.pdf