GlidePath Money

Use the BT Simulator to see what clearing a card does to your retirement

The 'what if I cleared this and put the money in retirement?' panel turns a payoff decision into three real numbers — tax savings, future value, and Monte Carlo delta. This shows you how to read each one.

By Jeff Intermediate 7 min read

You’ve got a 0% balance transfer card with a balance sitting on it. Should you put extra money toward clearing it, or should you put that extra money into your 401(k)? The honest answer is “it depends on the numbers.” The BT Simulator panel computes the numbers automatically, so you can see what clearing this card would actually do to your retirement plan — not as a guess, but as three specific live values.

This walks through reading the simulator and getting an actionable answer. The prerequisite is the Track a balance transfer walkthrough — if you don’t have a BT tracked yet, do that one first.

What you’ll learn

  • Where the BT Simulator panel lives on each active balance transfer
  • What each of the three numbers represents in plain English
  • How to compare the numbers and decide whether to accelerate payoff
  • Where the math comes from — every number opens to its own Explain view

Before you start

You need:

  • At least one active balance transfer tracked on /BalanceTransfers (see the prerequisite walkthrough)
  • The /Retirement page set up with at least a target retirement age and a marginal tax bracket (the simulator pulls both)

If the simulator panel says “Set up /Retirement first to see retirement impact,” that’s the only blocker — five minutes on /Retirement unlocks the full output.

What the simulator actually does

Below each active BT on the /BalanceTransfers page, GlidePath renders an inline panel titled ”💭 What if I cleared this and put the dollars in retirement?”. It assumes you accelerate the balance to zero in the current month (one large payment) and redirect the recurring payment going forward into your 401(k) or Roth.

It then shows three numbers, computed against your real data:

  1. Tax savings this year — how much income tax you avoid at your marginal bracket
  2. Future value at retirement — the freed-up dollars compounded to your retirement age
  3. Change in Monte Carlo success probability — how much your plan’s odds of lasting through retirement improve

Step 1 — Find the simulator panel (30 sec)

Open /BalanceTransfers. Each active BT row has an inline expand control labeled “What if I cleared this?”. Click it.

The panel slides open below the row.

Step 2 — Read “Tax savings this year” (1 min)

The first number answers: if I redirected the freed-up monthly payment into my 401(k) for the rest of the year, how much income tax would I avoid?

GlidePath computes it as:

Tax savings = monthly payment freed × months remaining in year × your marginal bracket

So if you’re freeing $400/month with 8 months left in the year, and you’re in the 22% federal bracket, that’s $400 × 8 × 22% = $704 in tax savings this year.

That’s the immediate, in-hand benefit. Real money you’d otherwise send to the IRS.

Step 3 — Read “Future value at retirement” (1 min)

The second number answers: if I redirect the freed-up payment into retirement for every month from now until I retire, what does that pile grow to?

GlidePath computes it as a compound future-value calculation:

Future value = monthly redirect × months until retirement × growth assumption (compounded)

The growth assumption defaults to 7%/yr, and it’s a nominal return — that is, before inflation. Inflation is its own separate input on /Retirement, so don’t mentally subtract it from this number too. The app’s own hint next to the input suggests a long-term average of 6-8% for a stock-heavy allocation; a bond-heavy mix usually warrants dialing it down. You can adjust it on /Retirement.

For someone 22 years from retirement, a $400/month redirect at 7% growth becomes about $226,000 at retirement — in future dollars, not today’s purchasing power. That’s the long-game benefit — the same dollars, just compounded for two decades instead of paying down a card you’re already at 0% on.

Step 4 — Read “Change in Monte Carlo success probability” (1 min)

The third number is the most interesting one. It asks: if I clear this card and redirect the payment, how much more likely is my retirement plan to last?

The simulator re-runs your retirement Monte Carlo (a 500-trial market-projection simulation) twice:

  • Baseline: with the card still on the books
  • Counterfactual: with the card cleared and the payment redirected

It compares the success rates and shows the delta.

A +2 to +5 percentage point improvement is typical for clearing a 0% promo card and redirecting the payment over a 20+ year horizon. For some plans the number is larger; for some it’s smaller. GlidePath doesn’t push you toward a specific decision — it just makes the tradeoff visible.

Step 5 — Compare the three numbers and decide (2 min)

Three real numbers, three different time horizons:

NumberTime horizonWhat it answers
Tax savings this yearThis calendar yearImmediate cash benefit
Future value at retirement10-30 yearsLong-term wealth impact
Monte Carlo deltaThrough end of planPlan robustness improvement

For most customers, this conversation reframes the BT-vs-401k decision from “which is more important?” (an emotional question) to “which lever moves the needle further?” (a quantified question).

The honest framing: when a BT is at 0% APR and you’re current on payments, the retirement redirect usually comes out ahead in the simulator; when a BT is about to flip to its post-promo APR, clearing it usually scores higher. The simulator doesn’t decide for you — it gives you the three lenses, and you decide.

What just happened

You’ve done something most personal-finance tools can’t do at all:

  1. Took one debt decision (whether to accelerate a BT payoff)
  2. Saw its impact across three time horizons (this year, retirement, plan robustness) in real dollars

This is the cascading what-if pattern that’s the model for everything else GlidePath is building. Change one input → see the ripple across multiple views immediately, all computed from your real data, all explainable.

Common follow-ups

The Monte Carlo delta says 0.0 percentage points. Why?

Either your plan is already at very high success probability (so there’s no room to improve) or very low (so this one BT isn’t enough to move the needle). Open the underlying Monte Carlo on /Retirement to see which case you’re in.

Why does redirecting to a 401(k) save more tax than to a Roth?

A 401(k) contribution reduces your taxable income dollar-for-dollar; a Roth contribution doesn’t. The tax-savings line uses the 401(k) assumption by default because that’s where most pre-retirees have contribution headroom. If you’d actually redirect to a Roth, the tax-savings line will be zero — but the Monte Carlo delta still applies, because the math doesn’t care about pre-tax vs post-tax growth in nominal terms.

Can I run the simulator on a BT I haven’t tracked yet?

Not yet. The simulator needs a real BT row to read the monthly payment + months remaining. Track the BT first (walkthrough), then expand the simulator.

My future-value number looks too high — what gives?

Check the growth assumption on /Retirement. The default is 7%/yr nominal; if you’ve set it to 10%, the future-value compounds faster and the number balloons. And remember the result is stated in future dollars — a big number two decades out buys less than the same number today, which is exactly why the Monte Carlo success change — which runs through the full retirement model rather than one compounding formula — is the more rigorous of the three numbers.

Ask Glide about this

Try: “Should I prioritize paying off a 0% BT or contributing to my 401(k)?” — Glide will walk through both sides of the tradeoff. Glide doesn’t see your numbers; it just explains the framework. The numbers come from the simulator panel.

Where to next