Yes, as a non-spouse beneficiary, you must withdraw all the funds and close the account by the end of the 10th year AND you must withdraw an RMD each year. You can't rollover or convert the funds to an IRA in your own name, it must remain as an inherited IRA ("John Smith as beneficiary of Mary Jones" or something like that).
The RMD is calculated a little differently than the RMD for your own IRA. You look at Appendix B, Table 1 in publication 590-B. Suppose you were age 50 in 2023 when the owner died. Your life expectancy was 36.2 years. Start with that figure and subtract 1 for each year forward. So in 2024, your RMD is the ending balance on 12/31/2023 divided by 35.2. Your RMD for 2025 is the ending balance on 12/31/24 divided by 34.2, and so on. https://www.irs.gov/publications/p590b
Also, note that even if you are under age 59-1/2, there is no 10% penalty for early withdrawal from an inherited IRA, just the regular income tax.
Remember an RMD is not a special withdrawal, it just means you have to withdraw more than that during the year. If you made a withdrawal in 2024 for any reason (living expenses, new car, whatever) that was more than the RMD amount, you already satisfied it.
If you did not withdraw anything, then you first need to withdraw the amount that would have been the 2024 RMD (today, if you did not already withdraw it). Remember this is your 2024 RMD so you still need to make your 2025 RMD withdrawal before 12/31/25.
Then, you need to file an amended 2024 return where you declare you missed the 2024 RMD and ask for a waiver. This is almost always granted, you just have to ask. You can write that you didn't know the rules for inherited IRAs, you took the withdrawal as soon as you learned the rules (in 2025) and will report the income on your 2025 return.
Then on your 2025 return, you will report both withdrawals as taxable income since they both happened in 2025. (The missed RMD is not taxable on your 2024 return, so you will not owe any additional tax with the 2024 return, you just need to file to get the waiver request taken care of.)
