Coast FIRE with a Pension: How a DB Pension Changes Your Number
If you or your spouse has a defined benefit pension — a teacher, nurse, government worker, military member — almost every FIRE calculator on the internet is overstating your target, often by five to ten times. Coast FIRE with a pension is not the standard formula with a bonus on top. It is a different calculation, and it is dramatically smaller.
A defined benefit pension is guaranteed retirement income, so your portfolio only needs to cover the gap between your spending and the pension — not your whole spending. Coast FIRE with a pension = (annual spending − annual pension) × 25, then discounted back to today. For a teacher couple spending $76,000 with a $69,000 pension, the target falls from $1.9 million to $175,000.
Why normal Coast FIRE math overshoots for pension holders
The standard coast fire calculation assumes your portfolio does all the work: you multiply annual retirement spending by 25 (the 4% rule), then work out whether your current savings will compound to that number by retirement without further contributions. Our guide on how to calculate your Coast FIRE number walks through that version.
But a defined benefit (DB) pension changes the job description. The pension is a stream of guaranteed income that arrives every year for life, usually with some inflation protection. Every dollar of pension income is a dollar your portfolio never has to produce. Treating a $69,000 pension as a nice-to-have footnote — which is what most calculators do, because they have no field for it — means calculating a target for income you already have.
This is not a small rounding issue. Public-sector workers with full pensions routinely believe they need $1.5–2 million to coast when their real number is a fifth of that or less. Some conclude Coast FIRE is out of reach when they have already passed it.
The gap method: three steps
Calculating coast fire with a pension takes one extra subtraction:
- Project the pension. Get the projected annual pension at your planned retirement age from your plan’s statement or online portal (OTPP, HOOPP, PSPP and most Canadian plans show this directly). Note whether the figure is in today’s dollars — most plan projections are, since they are based on your current salary history.
- Find the gap. Annual retirement spending minus annual pension income. This gap — not your full spending — is what your portfolio must cover.
- Apply the usual coast math to the gap. Multiply the gap by 25 to get the portfolio you need at retirement, then check whether your current savings compound there in time.
To check whether you can coast today, discount that target back: divide it by (1 + real return) to the power of years until retirement. If your current portfolio is at or above that figure, you can stop contributing and still arrive on time.
A worked example: the teacher household
Take a real-world shape we see constantly: a couple in Ontario, 35 and 37, spending $76,000 a year. One is a teacher whose pension will pay a projected $69,000 a year at 55. They have $432,000 invested and 18 years until that retirement date.
| Calculation | Target |
|---|---|
| Naive coast fire target ($76,000 × 25) | $1,900,000 |
| Gap after pension ($76,000 − $69,000) | $7,000 / yr |
| Gap method target ($7,000 × 25) | $175,000 |
The naive number says they are barely a quarter of the way there. The gap method says they passed their coast fire target with $432,000 already invested — more than double what they need at retirement, sitting in their accounts today, 18 years early. Same household, same spending, same pension. The only difference is whether the math acknowledges the pension exists.
Run your own gap
Enter the gap — spending minus pension — as your retirement spending in our Coast FIRE Calculator.
Practical tip: our Coast FIRE Calculator models RRSPs, TFSAs and taxable accounts, and the pension adjustment takes one substitution — enter your gap (spending minus pension) in the annual retirement spending field, and the calculator does the rest of the compounding and discounting for you.
The bridge benefit wrinkle
Many Canadian pensions pay a bridge benefit: a temporary top-up between early retirement and 65, when CPP and OAS are assumed to take over. A pension might pay $69,000 from 55 to 65, then drop to $59,000. That means the gap is not one number — it is $7,000 a year during the bridge years and $17,000 after.
The conservative move is to size your target on the larger, post-bridge gap: $17,000 × 25 = $425,000 at retirement. Discounted back 18 years at a 5% real return, that is about $177,000 needed today — still a fraction of the naive target. In practice the post-65 gap usually shrinks or vanishes on its own: the mortgage is typically paid off by then, and CPP and OAS start for both spouses. You can confirm your own CPP projection through your My Service Canada Account.
What CPP and OAS add
Everything above ignores CPP and OAS entirely, which is deliberate: they are your margin of safety. A couple with typical working careers can expect meaningful combined CPP and OAS from 65 onward — frequently $25,000–40,000 a year between them in today’s dollars, depending on contribution history and start age. If the pension-plus-portfolio math already works without them, government benefits turn a workable plan into a comfortable one. Counting them fully from day one, on the other hand, leaves you no slack if you retire earlier than planned or defer benefits for the higher payout.
Three honest caveats
- The pension assumes you stay. A projection at 55 is conditional on working to 55. Leave the plan early and you get a reduced pension or a commuted value transfer instead — if that is your plan, treat the commuted value as ordinary portfolio money and use the standard coast formula on the full spending number.
- Check the dollars. Confirm whether your plan’s projection is in today’s dollars or future dollars, and keep your return assumption consistent — mixing real and nominal figures is the most common way this math silently breaks. Our guide to real vs nominal returns explains the distinction.
- Indexing varies. Ontario Teachers’ and most large public plans index pensions to inflation; some plans index partially or conditionally. A non-indexed pension loses roughly a third of its purchasing power over 20 years at 2% inflation, so the gap grows — size the target on the later, larger gap if your plan does not index.
Who this changes the most
The gap method matters most for teachers, nurses, police, military, and federal and provincial employees — anyone in a DB plan — and for couples where one partner has a pension and the other does not. In those households the pension often covers most of the joint spending, which means the non-pension partner’s coast number is far lower than any generic tool will tell them. It is a common reason one spouse can afford to downshift to lower-stress work years before either of them realizes it. For the broader concept, start with our complete Coast FIRE guide for Canadians, or browse the rest of our free financial calculators.
Frequently asked questions
Yes, but not as a lump sum. A defined benefit pension is guaranteed income, so subtract it from your planned retirement spending and run the coast fire math on the remaining gap. Your portfolio only needs to cover what the pension does not.
Take your annual retirement spending, subtract the projected annual pension, and multiply the difference by 25. That is the portfolio you need at retirement. Then check whether your current savings will compound to that figure by your retirement date with no further contributions.
Only if you actually plan to leave the plan early and take the commuted value out. If you expect to stay until retirement eligibility, use the projected annual income — that is what you will actually receive, and it is usually worth far more than the commuted value suggests.
The same subtraction logic applies, but most planners treat CPP and OAS as a safety margin rather than counting them in the core math, because start ages are flexible and early-retirement years may not be covered. If your plan works without them, their arrival at 65 or later only makes it stronger.
Yes. The math is identical for any guaranteed income stream: subtract the annual benefit from annual spending and apply the 25x rule to the gap. US government and military pensions, annuities, and Social Security all reduce the portfolio’s job the same way.
Last updated: July 2026 · Uses the 4% rule / 25x convention and a 5% real return assumption in examples.
This article is general information, not financial advice. Pension terms vary by plan — projections, bridge benefits, indexing, and commuted value rules are specific to your plan and situation. Confirm figures with your pension administrator and consider professional advice before reducing savings or changing employment based on this math.
