Retirement tax questions

No, you should not list $0$ for his RMD. While the money was paid to you and your siblings, tax law considers the first dollars distributed from a deceased person's account in the year of their death to be "his" RMD first.

To determine what his RMD amount that should have been taken, you determine this by dividing the account balance as of 12/31/2024, and divide this by a Uniform lifetime Table amount. This can be found here. 

The next question is how to report this in TurboTax. Here is how to report on your father' return. For an example, if your father died at age 75 and the account balance from his Thrift Savings plan was $50,000, his RMD requirement would be.

$50,000 divided by 24.6 (from the table)= $2033.

1. Total RMD: Enter the full calculated amount (e.g., $2033). when it asks what was minimum amount the RMD should have been taken
2. Amount applied to RMD: Enter the $500 he actually received.
3. The software  flag that he didn't take enough (the remaining $1533).
4. The Waiver: The software will ask if you want to request a waiver of the penalty. Select YES. * The Explanation: In the explanation box, simply type: "Taxpayer passed away in March 2025. The remaining RMD was distributed to and reported by beneficiaries [Sibling Names] on their respective 2025 tax returns." This tells the IRS: "He didn't take it, but we did, and we are paying the taxes on it."
5. If you used TurboTax software, you will go to the Forms mode in your return. You will select 5329 on the list of forms and then go to the Waiver of Smart Tax Worksheet toward the bottom and submit your waiver request there.

On your return as well as your siblings.

1. Enter your 1099-R: You will receive a 1099-R in your own name/SSN.
2. Make sure that  Box 7 has a distribution code  4. This indicates this was an inherited IMD Question: When TurboTax asks if this was an RMD, select "Yes, all or part of this was an RMD."  
3. Then it will ask questions about what the required distribution should have been. This is determined by the formula I listed above.  
4. Just enter the same information as steps 1 and 2 above to determine the taxable amount that should have been paid by your father but is now passed to you.