A portion of my 2021 RMD ($1687.73) was paid to US Treasury to cover 4th estimated tax voucher. Where do I report this?

[DoninGA]

To enter, change or delete a payment made with an extension request (Federal, State, Local) -

• Click on Federal Taxes (Personal using Home and Business)
• Click on Deductions and Credits
• Click on I'll choose what I work on (if shown)
• Scroll down to Estimates and Other Taxes Paid
• On Income Taxes Paid, click on the start or update button

On the next screen select the type of extension payment made and click on the start or update button

Or enter federal extension payment in the Search box located in the upper right of the program screen. Click on Jump to federal extension payment

The federal extension payment will be shown on Schedule 3 Line 10. The amount from Schedule 3 Part II Line 15 flows to Form 1040 Line 31

[Mike9241]

when you enter your 1099-R there should be a question about federal withholding which is line 4 on the 1099

[fanfare]

you need to explain more about how the payment was made to know which line of 1040 this goes on.

@lewschoyen 

[Critter-3]

Either you had withholding from the IRA which will be reported on the 1099-R box 4   OR   you took the RMD out, put it in your checking account and then made an estimated payment ... where to enter both situations was already posted in this thread.   If you did something else you will have to explain what you did in more details.