Stress Testing Guide
Stress testing helps you answer one question: will my retirement plan still work if things go wrong? This guide explains how to use the calculator’s built-in stress tests step by step.
Why stress test?
A retirement plan is built on assumptions – about inflation, investment returns, and how long you will live. If those assumptions turn out to be optimistic, a plan that looked comfortable can fall short. Stress testing checks the “what ifs” before you retire, so you can adjust while you still have time.
How to select and run stress tests
On the Results step, open the Stress Tests panel.
Tick one or more built-in scenarios, such as Higher Inflation or Longer Life Expectancy.
Choose Run selected to test the ones you ticked, or Run all to test every scenario.
Each scenario is applied to a copy of your plan. Running a test never changes your core inputs, so you can experiment freely.
How to edit a stress test
You can fine-tune any built-in test:
Open the test you want to change.
Adjust its parameters and the mode (see below).
Save your changes.
How to create a custom stress test
Want to model a risk that is not in the built-in list? Create your own:
Choose Create new test.
Give it a name and a risk category.
Add one or more parameters, each with a mode and value.
Save and run it like any other test.
The three parameter modes
Each parameter changes a value in one of three ways:
Add – shifts a value by an amount (for example, +1% inflation).
Set – replaces a value with an exact number (for example, 3% returns).
Scale – multiplies a value by a factor (for example, 1.2x life-expectancy growth).
How to interpret the results
For every scenario you see how five outcomes changed versus your baseline:
Depletion age – when your portfolio would run out (blank means it survived).
Final portfolio value – what remains at the end.
Total taxes paid – lifetime tax burden.
Average tax rate – your effective rate.
Sustainable withdrawal – the income your plan supports.
A red value means the scenario hurt that outcome; green means it helped.
Isolated vs stacked runs
Run selected / Run all tests each scenario on its own so you can see its individual impact.
A stacked (combined) run applies several tests together to model a worst-case “perfect storm”.
How to apply a stress test to your core scenario
When a stress test reveals a change you want to keep permanently – for example, retiring a few years later – use Apply to core scenario. This overwrites your baseline inputs with the stressed values. Use it only when you are sure.
How to reset a test
If you have edited a built-in test and want the original values back, choose Reset to default. This restores the built-in values for that test. Custom tests you created are not affected.