I wasn’t going to comment because I don’t have kids, but…. I think my qualm is that FIRE with two living parents is unlikely to be FIRE with only one. Not making assumptions about gender roles or who passes, but if the person who cooks passes, the food budget will go up. That is, you may not need the working income of the deceased spouse, but you need the life skills. If your kids are older you may not need babysitting per se, but again may be more likely to order pizza because you need downtime from single parenting. What about homework, the deceased parent was the math whiz you might be paying for tutoring. Just my two pennies.