How do I alert the IRS that we missed taking out the 2023 RMD from an inherited IRA. We misinterpreted the new rule about someone not having to take it out until they turn 73. My wife doesn't turn 73 until next year, however we found out the old rule applies since she has been taking it out every year. I have typed a letter asking for a waiver for reasonable cause. Should I send the letter and the withdrawal to the IRS?