@Anonymous
No, there is no exception in the law, regulations or publication 590-B for additional tax for missing an RMD. However, the IRS may grant a waiver for "reasonable cause", including illness. Which is what I wrote.
Here is the law.
https://www.law.cornell.edu/uscode/text/26/4974
An exception is something written into the law. It's automatic, the law is whatever the law says. For example, the law says you don't pay the 10% penalty on early withdrawals if you meet a certain definition of disabled. There's no discretion involved and you don't have to ask, you just follow the law.
A waiver is discretionary administrative relief. Although the ability to grant waivers must be authorized in the law ("the Secretary may waive the tax"), it is not guaranteed, and depends on the discretion of the person reviewing the form and the overall position of the IRS. Recently, the IRS has been generous about granting waivers of the penalty, but this is not permanent or guaranteed, it can be changed at any time. For example, if the president appointed a new commissioner of the IRS who wanted to squeeze every dollar out of every taxpayer, they could change the policy and start refusing to grant waivers of the tax for missing an RMD. The law says the IRS may waive the penalty, it does not say the IRS must waive the penalty. On the other hand, the IRS can't change the exception to the 10% penalty for early withdrawal for people who meet a certain definition of disabled, because that is written into the law and only Congress can change it.
As I said, a person can use illness as reasonable cause to request a waiver. That is not the same as an exception.
