Yeah, I don't think this would work out too well. Along with reasons that others have mentioned including penalties for early withdrawal before age 59.5 from retirement plans (However, principal contributions older than 5 years contributed to a Roth IRA can be withdrawn at any time), there are others. The 4% rule assumes you are retiring at a traditional retirement age (65ish). You are adding 20 years to your retirement life that the $1M will have to cover. Also, your kids would be around 15 years old or younger when you retire. Your family health insurance premiums will be at least $1,000 a month, probably closer to $2,000 (and you won't be eligible for Medicare until 65). Also, your SS benefits will be greatly reduced when you finally are eligible to collect it since SS is based on highest 35 years of pay. If you retire at age 45, you may have 25-30 years of pay at the most (based on the current way SS works). As a side note, the 4% rule is questionable. If you Retire at 65 and have $1M and use the 4% rule, the $1M principal would get you to age 90 (assuming it's 4% of your initial retirement amount and not 4% of the amount at the end of each year) . So, it seems to assume that you just move all the money to cash when you retire. That would be a foolish move. You should be at least at 50/50 (50% Equities/50% fixed) or 40/60 in retirement.