This is the “show your work” post in the series. If you came for the FIRE strategy you can happily skip it; if you want the Roth conversion optimization written out as an actual linear program — decision variables, constraints, objective — this is for you. It mirrors the Excel + OpenSolver model I described in part 2.
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How Much Should I Convert to a Roth Each Year?
This post is about a question I keep circling back to as an early retiree: how much to convert to a Roth in any given year. Not whether to convert — I’m already sold on that — but the actual dollar amount, year by year. It turns out to be a surprisingly good little optimization problem, and this is how I think about it.

The Roth Conversion Ladder (and Its Blind Spot)
If you retire before 59½ with most of your money locked in a traditional IRA or 401(k), you run into an awkward problem: the money is there, but reaching it normally means a 10% early-withdrawal penalty on top of income tax. The Roth conversion ladder is the classic FIRE workaround, and it is the setup for everything else I want to write about in this series.
Continue reading “The Roth Conversion Ladder (and Its Blind Spot)”The Best Time to Convert a 401(k) to a Roth IRA
If you’re asking what the best time to convert a 401(k) to a Roth IRA is, here’s the short answer: it’s not a date on the calendar, it’s a low-income year. A conversion is taxed at your marginal rate the year you do it, so the entire game is converting when that rate is as low as it will ever be. Get the timing right and you move money to the tax-free side cheaply; get it wrong and you hand the IRS more than you needed to.
Continue reading “The Best Time to Convert a 401(k) to a Roth IRA”In-Plan Roth Conversion: Convert Inside Your 401(k)
An in-plan Roth conversion lets you move pre-tax money in your workplace retirement account into the Roth side of that same account, without rolling it out to an IRA. You’ll also see it called a “Roth in-plan conversion” or, in IRS language, an in-plan Roth rollover. Whatever the name, the idea is the same: take traditional 401(k), 403(b), governmental 457(b), or TSP dollars, pay the tax now, and let them grow tax-free from here.
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