How The Retirement Modeler Works

Why Your Retirement Spreadsheet Is Giving You a False Sense of Precision

A spreadsheet projects one outcome. You plug in an assumed return — say 6% annually — and it draws a smooth line from today to age 90. That line is not a forecast. It is an assumption with formatting.

Real retirement involves dynamic variable cash flows: income that changes each year as Social Security kicks in, as pensions adjust, as you reduce spending in your eighties, and as Required Minimum Distributions force qualified account withdrawals whether you want them or not. None of that fits in a single-rate projection.

The Retirement Modeler replaces the spreadsheet with a month-by-month simulation engine. Each month is calculated individually — fixed income arrives, the gap is computed, and assets are drawn from in the optimal tax order. The result is not a line. It is a schedule, and it is honest about uncertainty.

Monte Carlo Simulation & Success Probability

The base model runs your inputs through a deterministic forecast — a single path using your stated return assumption. The Monte Carlo engine does something different: it runs hundreds of randomized market simulations, each with a different sequence of annual returns drawn from a distribution centered on your stated assumption.

The output is a Monte Carlo success probability — the percentage of simulated scenarios in which your assets survive to age 100. This is probabilistic retirement forecasting, not a single-number guess.

The three percentile bands shown (conservative, median, optimistic) represent the bottom 10%, the middle, and the top 90% of outcomes. They give you a realistic range — not just the average scenario you're hoping for.

Sequencing of Returns Risk: The Hidden Threat in the Retirement Red Zone

Sequencing of returns risk is one of the most consequential and least understood risks in retirement planning. It refers to the danger that poor market returns early in retirement permanently damage a portfolio — even if the long-run average return looks acceptable.

Here is why it matters: a 25% loss in year two of retirement forces you to sell more shares at depressed prices to cover living expenses. Those shares are gone and cannot participate in the eventual recovery. The same 25% loss in year fourteen is far less damaging — your portfolio has had years to grow, and you are drawing from a larger base.

The five-year window straddling your retirement date — roughly two years before to three years after — is sometimes called the retirement red zone. Poor returns in this window are disproportionately destructive.

This is exactly what the Monte Carlo engine stress-tests. Each simulated path represents a different sequence of returns across your retirement horizon. The success rate reflects how often your plan survives bad sequences — not just average ones.

Three-Bucket Tax Strategy: Dynamic Variable Cash Flows Across Account Types

Most retirement calculators treat all assets as a single pool. The Retirement Modeler separates them into three tax buckets and draws from each in the optimal order — minimizing lifetime taxes by spending the right dollars at the right time.

The draw order functions as an income bridge strategy — exhausting lower-value assets first while allowing tax-advantaged balances to compound. The result is a materially lower cumulative tax burden over a 30-year retirement horizon.

Safe Withdrawal Rates and the Limits of the 4% Rule

The 4% rule — withdraw 4% of your initial portfolio each year, adjusted for inflation — became popular because it was simple. Research suggested it survived most 30-year historical periods. But it has real limitations that make it a poor substitute for personalized analysis.

• It assumes a 30-year horizon. Many planners should model through age 95 or 100.
• It ignores taxes. A 4% withdrawal from a pre-tax IRA delivers less than 4% after federal and state income tax.
• It ignores Social Security and pension income, which reduce the portfolio draw requirement in later years.
• It assumes a fixed dollar amount. Real spending is not fixed — it changes with inflation, health, lifestyle, and RMD requirements.

The Retirement Modeler computes your actual safe withdrawal rate dynamically, accounting for taxes by source, fixed income offsets, and year-by-year draw requirements — rather than applying a static multiplier to your opening balance.

No Linked Accounts. No Financial Data Aggregation.

Financial data aggregation services — tools that link directly to your bank, brokerage, or retirement accounts — require you to hand over your credentials or authorize third-party access to your financial institutions. The Retirement Modeler takes the opposite approach.

We never ask for account numbers, institution names, Social Security numbers, exact birth dates, or any information that could identify you to your financial provider. You enter balances as a single number. We run the simulation. That is the entire data relationship.

This is not a limitation — it is a deliberate design choice. Your financial plan should not require surrendering access to your financial accounts to a third-party modeling tool. The numbers are yours; the model is ours.

What a 1% AUM Fee Actually Costs Over a Retirement Horizon

A financial advisor charging a 1% AUM fee on a $600,000 portfolio costs $6,000 in year one. If that portfolio grows to $700,000 in year two, the fee is $7,000. Over a 25-year retirement, the cumulative cost of a 1% annual fee compounds significantly — not just in dollars paid, but in the growth those dollars would have generated had they stayed invested.

This is not an argument against working with an advisor. Many advisors provide meaningful value in estate planning, tax coordination, and behavioral coaching. The point is that you should walk into those conversations with your own analysis — not rely solely on projections your advisor generated using your money as the fee base.

The Retirement Modeler is built for people who want to stress-test their plan independently, understand the assumptions behind any projection they are shown, and make informed decisions about how and when to engage professional guidance.

Frequently Asked Questions