JRTN Tool

JRTN is a Microsoft Excel based tool. The core of the tool is a model spreadsheet that fully exposes the calculations associated with annual spending determination. Available spending is ultimately controlled by external income sources and by draws against various accounts (and of course by income taxes). The draws are captured as a few input columns in the model spreadsheet. Automation is provided to adjust the draws to meet after tax spending needs. This requires an iterative solution approach because there is no reasonable closed form solution. A user can avoid the automation completely and manually set the draws if desired. This might be a first step at using JRTN to “build their own worksheet.” Substantial additional automation supports activities such as scenario comparison, maximum spending calculation, Roth conversion optimization, etc.

The user interface is forms-based, however the user is required to populate input data such as account values, expected rates of return, etc. directly into a spreadsheet.

The central notion for JRTN is that we need to look at multiple scenarios to make our choices and to understand possible future outcomes. For example, we should look at both low and higher inflation levels, low and higher rates of return, etc. JRTN has rich scenario support including the automatic Scenario generation via permutation of control parameters, scenario summaries, and graphical scenario comparison.

• High fidelity tax calculations for both Federal and State
• Automatic draw calculation to reach specified after-tax spending
• Automated Scenario Generation – generate 1000s of scenarios by permuting parameters such as inflation, ROI, SS commence
• Independent and dependent parameters for scenario generation. For example, you can tie “moving to a different State” with “change in expenses.”
• Maximum Spending Calculation
• Roth Optimization and Analysis Tools
• Social Security Break-Even
• Single and Married Retirees
• Support for potential Federal tax law changes
• Configurable State Tax rules. This is done via a worksheet that specifies rules for each state, so users typically just pick the state
• Support for future state (tax jurisdiction) change
• Single vs Married Expense Profile
• Graphical reports
• Pension/Annuity income sources with parameters for inflation adjustment and survivorship
• Administrative tools such as the capture of all relevant parameters to a parameter file
• Developer tools including various logs and comparison tools.

JRTN is licensed via the Apache 2.0 license. The details of what you can and can’t do with this license are specified in the license specification. That said, this is a relatively permissive license; you can pretty much do whatever you want with JRTN so long as copyright information is maintained. For example, you could create a derivative work if desired.

JRTN has been a retirement hobby project. The initial motivation was to gain a better understanding of my own situation. After that it took on a certain entertainment value as I have always loved programming and spreadsheets. There is just enough code and enough coding challenges to be “interesting.” More recently the JRTN tool has been a research vehicle for the associated manuscript. I have moved forward to publish the tool because adds to the entertainment factor as the problem scope for a generally useful tool is bigger than what I personally need. Beyond that, it is fun to do something that is at least potentially “useful.”

There are many great retirement tools available. Some are free, some are inexpensive, and some are relatively expensive. I believe that JRTN adds a bit, especially at the free end of the spectrum. See for example Roth Conversion optimization and high-fidelity tax computation. There are no plans to risk that calculus by trying to monetize JRTN.

• V 1.02 – (Late 2024)
  • Performance Tuning
  • Eliminated “Roth Conversion Payback”
  • Made Roth Conversion Opt. and Max spending scenario controls
  • Additional tools for Roth analysis
  • Profile Management
  • Analysis tools
  • Eliminated hardcoded names for Model, etc

• V 2.0   – (June 2026)
  • Updated for OBBB act and 2026 state tax laws
  • Moved local tax out to model, revert to single StateTaxInfo
  • Roth Conversion Tax source control
  • More Performance tuning
  • Generalized “future tax law” prediction
  • Proper LTGC (don’t assume 15%)
  • Asset Ratio Capture