How the model works

Short notes on LadderUp’s income-first retirement model: the Security Ratio, TIPS bond ladders, Social Security claiming, and how to read the simulation results.

These notes explain the LadderUp retirement-planning framework in plain language. They are the best place to learn what the research prototype is doing before you read the working paper or run the model.

• Why this planner exists

  LadderUp treats retirement as an income problem, not a portfolio-size problem. Learn why wealth targets and the 4% rule leave future spending exposed to markets.

• Stocks and bonds in this model

  How LadderUp uses stocks to build future income and TIPS held to maturity to lock it in—unlike target-date funds and bond ETFs that still carry interest-rate risk.

• The security ratio

  The Security Ratio measures how much of your desired retirement income is already guaranteed. See how SR, SR0, and income smoothing shape retirement readiness.

• When can you retire?

  LadderUp says you can retire when income capacity covers your goal and the Security Ratio hits your target—not when a portfolio number is reached.

• Social Security in the model

  How LadderUp estimates Social Security benefits and lets claiming age emerge from the simulation when those benefits improve retirement readiness.

• Reading your results

  How to read LadderUp plan summaries, glide paths, income charts, and percentile tables after you run the Monte Carlo allocation solver.