72(t) / SEPP early-withdrawal schedule

Substantially Equal Periodic Payments under §72(t) let someone draw an IRA before age 59½ without the 10% early-withdrawal penalty. Computes the annual payment under the RMD and fixed-amortization methods (both on the IRS Single Life Table), the recommended (largest) figure, the required duration (the longer of five years or until age 59½), and the worst-case retroactive penalty if the plan is busted. The amortization rate defaults to the 5% statutory floor (always allowable); pass a higher rate up to the greater of 5% or 120% of the mid-term AFR to lift the payment. The fixed-annuitization method is not modeled. Deterministic; not tax advice.