I presume that the RMDs will be stopping until the account is transferred to a beneficiary account for you, which will probably take at least a few days after you provide the death certificate if you keep it at the same brokerage - longer if you want to transfer to another brokerage. For 2023, the total taken out of the account must be at least the RMD amount that your Mom was required to take. So be sure that for 2023, the total distributions that she had received plus the distributions that you receive total up to at least the RMD that she was required to take in 2023. You will have to take out enough to make up for any of the distributions that were missed while they were temporarily stopped, and these distributions must occur by Dec 31, 2023.
For future years, you will take out RMDs based on Table I (Single Life Expectancy) in IRS Pub 590-B 2022 Publication 590-B (irs.gov) For 2024, you will start with your age as of your birthday in 2024. For example, if you will turn 60 in 2024, your life expectancy will be 27.4 years. 1/27.4 = 0.365 or 3.65%, so you would need to take at least 3.65% of the account balance as of Dec 31, 2023. Then, each year after that, you will subtract 1 from the 27.4 and use that as your denominator. So for 2025, 1/26.4 = 3.79%, so you would take out at least 3.79% of the balance as of Dec 31, 2024 Then, because you need to empty out the account by the end of 2034, in 2034, you will need to take the remaining balance out, so it’s down to $0 by the end of 2034. If you have anything that pays end of year dividends, you should be sure that they will distributed to you by Dec 31, 2034. (If you will turn an age other than 60 in 2024, you will need to substitute the life expectancy from Table I for the 27.4 in the calculation.)
If, for tax planning purposes, you don’t want to leave a large balance to be taken out in 2034, you could take 1/10 of the Dec 31, 2023 balance out in 2024, then take 1/9 of the Dec 31, 2024 balance out in 2025, repeating through 2034, when you would distribute the entire balance.
Or you could empty out the entire account any time before the end of 2034, for example, if you want to take a grand vacation or buy a new car courtesy of Mom. Just be sure to take minimum RMDs until the year you do the total distribution, and be sure to adjust any estimated tax payments to avoid underwithholding penalties.
AJ