Your dashboard says the plan is fully funded to age 95. Monte Carlo comes back at 22% confidence. One of these numbers is wrong, surely? Actually, no. Here's why both can be right at the same time — and how to know which one matters for your plan.
Imagine two people, same retirement age, same income goal. One runs their plan and sees 85% Monte Carlo confidence. The other sees 22%. Neither has done anything wrong with their inputs. Neither has a fundamentally broken plan.
The difference is what their plans are made of.
Monte Carlo applies random shocks to your investment accounts — your pension pot, your ISA — each year of each simulated future. In a bad year, those accounts take a hit. In a good year, they grow more than expected. Run the whole projection 1,000 times with 1,000 different sequences of good years and bad years, and you see the range of possible outcomes. The confidence score is simply: in how many of those 1,000 futures did your income need get met?
Here's the key detail: the size of those shocks depends on what type of account it is. A DC pension in global equities gets the full volatility setting you've chosen — because equity markets really do swing dramatically from year to year. A savings account gets one-sixth of that. Because cash doesn't.
So if your plan is mostly state pension, savings, and rental income — steady, predictable sources — Monte Carlo has very little to stress-test. The random shocks are tiny. But over 30 or 35 years, even tiny shocks accumulate, and a handful of the 1,000 simulations eventually clip a shortfall somewhere late in the projection. Crucially, those "failed" simulations are almost always what the engine calls distressed outcomes: the plan struggled to meet your target spend in some years, but you still ended up with money in the bank. They are not ruin. The confidence score falls — but the plan hasn't broken. The real risk in a cash-heavy plan isn't the small market variance; it's whether the plan can handle long-run inflation — and that is exactly what the dashboard is already testing.
When the dashboard shows a green tick and "Plan fully funded to age 95", that's not a rough estimate or a best-case guess. Think of it as a month-by-month cashflow stress test. The projection engine runs from today to your life expectancy — every month. Every month it inflates your spending target for that year's assumed inflation, adds up your guaranteed income, and draws from your flexible accounts in your chosen order to cover any remaining gap. If the income need is met every single month — including 30-plus years of inflation eating into your spending power — the verdict is "fully funded".
That's a genuinely demanding test. It doesn't assume anything averages out. Every month is run explicitly, with inflation compounding year by year, with your actual account balances, in your chosen draw order. If the projection passes, it passes every single month — not on average.
For a plan where the income sources don't fluctuate meaningfully — where state pension, a defined benefit pension, or rental income are doing most of the work — that deterministic test is the one that matters. The answer is already the answer.
The source of confusion: the dashboard asks does the arithmetic hold? Monte Carlo asks does it hold under market turbulence? For a cash-heavy plan, the first question is the meaningful one. The second question is technically answerable but not very useful — there isn't much turbulence to worry about.
Most of your wealth is in a DC pension invested in equities, with limited guaranteed income. The standard projection shows the middle-of-the-road case using fixed growth rates. What it can't capture is what happens when markets have a rough patch early in retirement, when your pot is at its largest and you're drawing from it. A 20% fall in year one does far more damage than the same fall in year fifteen — and Monte Carlo measures exactly that. If Lifestyle Confidence is below 70%, check the Survival Probability next. If both are low, the plan needs attention. If confidence is modest but survival is high, you have resilience — the question becomes whether to de-risk rather than whether the plan is broken.
Most of your wealth is in savings and ISAs, with significant state pension, DB pension, or rental income. Monte Carlo will show a lower Lifestyle Confidence than you might expect — and that's normal. It reflects the fact that even small standard deviations in cash accounts accumulate into occasional simulated shortfalls over 30-plus years, which the engine registers as a failed run. Most of those failures are distressed outcomes — target missed in some years, but money remained at the end — rather than ruin. Check the Survival Probability: in a cash-heavy plan it will almost always be very high, which confirms the dashboard's verdict.
What to focus on: is the plan fully funded? Is there a meaningful balance remaining at plan end? Does the cashflow chart show income meeting the spending target year by year?
You have a mix of equity pension wealth and savings or ISA, plus some guaranteed income. The guaranteed income (state pension, DB, rental) provides a floor that Monte Carlo never touches — it's fixed in every simulation. Think of the Lifestyle Confidence score as a market-risk-adjusted reading for the flexible portion of your wealth: it isn't testing whether your DB pension holds up, only whether your DC pot or ISA can cover the remaining gap when markets are unkind. The Survival Probability tells you something different again — how often that gap was bridged with anything rather than nothing. Both views are informative here: the dashboard tells you whether the total plan works; Lifestyle Confidence tells you how reliably the equity portion earns its keep; Survival Probability tells you whether genuine depletion is ever on the table.
Monte Carlo produces two numbers that matter, and they answer different questions.
Lifestyle Confidence is the percentage shown in the dial — the share of 1,000 simulations in which your plan met your full target income every month. This is deliberately demanding. It asks whether the retirement you designed is achievable under market turbulence, not just on average. Think of it as your Plan A resilience: how often does the life you planned actually materialise?
Survival Probability is the figure in the outcome breakdown — the share of simulations in which you never exhausted your money entirely. It is the inverse of the ruin rate: if 3 out of 100 simulations ended in full depletion, your Survival Probability is 97%. Think of it as your safety net assurance: even when the plan doesn't go perfectly, how often do you still land on solid ground?
A plan that shows 65% Lifestyle Confidence and 97% Survival Probability is not a fragile plan. It means: in 35% of simulated futures, you'd have had to trim spending — perhaps forgoing a holiday, perhaps drawing savings a year earlier than planned — but in 97% of futures, you never came close to running dry. The gap between "missed my target" and "ran out of money" is where most real retirements actually live.
The only number that signals a genuinely broken plan is the Survival Probability falling to a level you find unacceptable. A low Lifestyle Confidence score, without a correspondingly low Survival Probability, means the plan is imperfect — not dangerous.
Run the dashboard first. Check the plan is fully funded, look at the cashflow chart, note the balance at plan end. This tells you whether the basic arithmetic holds.
Then run Monte Carlo and read both numbers. If Lifestyle Confidence is high — say 70% or above — your plan handles market volatility well. If it's lower, check the Survival Probability immediately. A modest confidence score paired with a high Survival Probability is a plan that may ask you to adjust spending in some scenarios, but will not ask you to sell your house. Then ask: how much of my wealth is genuinely in volatile investments? If the answer is "not much", the dashboard result remains the more relevant conclusion and the lower confidence score is expected behaviour, not a warning.
Neither number is wrong. They're answering different questions. Lifestyle Confidence asks whether you'll live the retirement you planned. Survival Probability asks whether you'll have resources at all. Knowing which question matters for your situation is what lets you read both correctly.