What happens if I break a 72(t) plan by taking out too much or too little?

Breaking a 72(t) is costly. If you modify the substantially equal periodic payments before the required period ends, generally five years or until age 59.5, whichever is later, the IRS retroactively imposes the 10% early-withdrawal penalty on all the distributions you already took, plus interest. That can turn years of penalty-free income into a large surprise bill. Mistakes that trigger this include withdrawing a different amount than the schedule allows, rolling the account over, or adding money to it. Because the plan is so rigid, a common safeguard is to split your IRA before starting, putting only enough into the SEPP account to generate the income you need and leaving the rest untouched for flexibility. The IRS does allow a one-time switch to the RMD method, which can rescue a plan that has become unaffordable, but otherwise the rules leave little room for error.