Assumed vs Inherited IRAs

My mother assumed a traditional IRA from her deceased husband. She assumed the IRA in 2025. Her husband died in 2024. She took an RMD from the assumed IRA in 2025. 

 

When putting the 1099-R into TurboTax Desktop, there is an interview question "Do any of these situations apply to you?" There is a box titled "I inherited this IRA". If I check it, it looks like the distribution is not taxed. If I don't check it, the distribution seems to be taxed. 

 

Researching with IRS - I think the distribution should be taxed as ordinary income. 

 

Does anyone now what the "I inherited this IRA" box means or when it is used?

 

Thanks. 

 

Eddie.