This is the part of the series I’m most excited about: turning my spreadsheet into free, online Roth conversion software — really an optimizer — that you can run on your own numbers, without owning Excel or knowing what a solver is.
This is a 4-part series on optimizing IRA-to-Roth conversions in early retirement:
- Part 1: The Roth conversion ladder (and its blind spot)
- Part 2: How much should I convert each year?
- Part 3: The optimization model behind it
- Part 4: A free Roth conversion tool (coming soon) (you are here)
Right now the model from part 2 lives in an Excel file driven by Solver and OpenSolver. It works, but it’s locked inside Excel: I can’t hand it to a reader, it won’t run on a phone, and you’d need the right plugins installed to even open it. That’s the same wall I’ve hit with every model I’ve built over the years.
I’ve done this before
This won’t be my first Excel-to-web conversion. I’ve already taken two other optimization models out of spreadsheets and put them online as small web apps:
- A staff scheduler that assigns people to shifts at minimum cost.
- A vehicle-routing solver that plans delivery routes with time windows and truck capacities.
Both started exactly where this one is — a working spreadsheet — and both now run in a browser. The recipe is the same each time, and I’ve written it up step by step in the OR-tools series on this blog.
The plan for this one
Because the Roth conversion model is a small, clean linear program (see the formulation), the port is straightforward:
- Rebuild the model in Python using PuLP, the same CBC solver engine OpenSolver uses under the hood.
- Wrap it in a small Flask app with a simple form: your ages, balances, expected return, other income, and spending.
- Deploy it on Render so anyone can use it for free, and let you download the year-by-year conversion plan it produces.
My goal is a tool where you type in a handful of numbers and get back a suggested conversion amount for each year — a concrete starting point you can take to your own CPA, not a black box that tells you what to do.
Want it tuned to your situation?
Before I build it, I’d love to know what would make it actually useful to you. What inputs matter most for your plan? ACA subsidy cliffs? IRMAA brackets for Medicare? State income tax? Drop a comment and I’ll try to fold the most-requested pieces into the first version. When it’s live, this post is where I’ll link it.
One disclaimer, because this is money and taxes: I am an operations research analyst, not a CPA or a financial advisor, and nothing here is tax or investment advice. This is just how I think about my own situation. Tax rules change and your situation is different from mine, so check the primary sources and talk to a professional before you actually move money.
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