To calculate your FIRE number with a pension, subtract the annual pension from your planned spending and multiply what’s left by 25 (a 4% withdrawal rate). If you’ll spend $75,000 a year and your pension pays $30,000, your portfolio only has to cover $45,000, so your FIRE number is $1,125,000 instead of $1,875,000.
That shortcut only works if the pension starts the day you retire. If you retire at 45 and the pension starts at 60, you need a second piece: a bridge fund that covers your full spending until the first check arrives.
Why a pension changes the FIRE math #
A standard FIRE number assumes your portfolio pays for everything. A pension takes over part of that job for life.
- Your target shrinks, often by hundreds of thousands of dollars.
- Sequence-of-returns risk drops, because part of your income doesn’t depend on markets.
- You can often hold more stocks, since the pension works like a large bond holding.
Method 1: the pension starts when you retire #
FIRE number = (annual spending − annual pension) x 25
- Spending: $75,000
- Pension: $30,000, starting immediately
- Gap: $45,000
- FIRE number: $45,000 x 25 = $1,125,000
Without the pension, the number would be $1,875,000. The pension is worth $750,000 of portfolio.
This fits military retirees, some public safety and government workers, and anyone retiring at their plan’s normal pension age.
Method 2: the pension starts later (bridge plus core) #
Most early retirees face a gap. Say you retire at 45 and the pension begins at 60. Split your money into two jobs.
The core portfolio #
At 60 you’ll need enough to cover the $45,000 gap for life: $45,000 x 25 = $1,125,000. If you leave that money invested and untouched from 45 to 60, at a 5% real return you need only about $541,000 at 45 for it to grow to $1,125,000.
The bridge fund #
From 45 to 60 you need your full $75,000 a year. Because this fund only has to last 15 years, it can spend down to zero. At a 4% real return, that takes about $834,000 at 45.
The total #
$541,000 + $834,000 ≈ $1,375,000 at age 45, compared with $1,875,000 if you ignored the pension. The bridge is the expensive part, which is why the pension’s start age matters so much.
Retire Goals doesn’t model pensions directly, but its calculators cover both pieces. Enter your spending minus the pension into the FIRE Number calculator for the core figure. Then check the bridge with Will My Money Last: enter the bridge balance and your full spending, and it shows how many years the money lasts with withdrawals rising for inflation. If it’s short of your gap years, you know which number to grow.
Adjust for inflation, taxes and risk #
Does your pension have a cost-of-living adjustment? #
- With a COLA: benefits rise with inflation, common in government and military pensions. You can treat the current dollar amount as today’s dollars.
- Without a COLA: a fixed payment loses buying power every year, both before it starts and after. At 3% inflation, a $30,000 pension that starts in 20 years is worth about $16,600 in today’s money on day one, and keeps shrinking from there.
For a fixed pension, subtract a smaller, inflation-adjusted figure from your spending, or plan for your portfolio to cover a growing share of spending later in retirement. Our guide to adjusting your FIRE number for inflation explains the math.
Taxes #
Pension income is usually taxed as ordinary income, and state treatment varies widely. It also fills your low tax brackets, which can make later IRA withdrawals or Roth conversions more expensive. Add your expected taxes to your spending.
How safe is the pension? #
Government pensions are backed by public funds, though some plans are badly underfunded. Most private defined-benefit pensions are insured by the Pension Benefit Guaranty Corporation up to legal limits, but a high benefit from a failed plan can be cut. If your plan looks shaky, discount the expected payment by 20% to 30% in your math.
Survivor options #
Choosing a joint-and-survivor payout lowers the monthly amount but keeps paying your spouse after you die. Plan around the payment your household will actually get.
Leaving early can shrink your pension #
Most defined-benefit pensions use a formula like:
annual benefit = years of service x multiplier (often 1.5% to 2%) x final average salary
Leave at 40 instead of 60 and you have fewer years of service and a final salary frozen at a younger, lower level, which in many plans isn’t adjusted for inflation before payments begin. Ask HR for a vested deferred benefit estimate: what you’d receive at eligibility age if you left today. Use that figure, not the one on your annual statement that assumes you stay until 62 or 65.
Pensions and Social Security #
If your pension comes from a job that didn’t pay into Social Security, as with some teachers, police officers, firefighters and older federal employees, your Social Security used to be cut by the Windfall Elimination Provision and Government Pension Offset. The Social Security Fairness Act, approved on January 5, 2025, repealed both for benefits payable for months after December 2023. If you’d written off part of a Social Security benefit because of those rules, rerun your numbers. Our guide to early retirement math with Social Security shows how to layer it in.
Lump sum or monthly payments? #
Some plans offer a lump sum instead of a lifetime pension.
- Monthly payments give you guaranteed income for life, protect against outliving your money and reduce market risk.
- A lump sum rolled into an IRA gives you control and something to leave heirs, but you take on the investment and longevity risk yourself.
Compare the lump sum with what it would cost to buy a similar lifetime annuity. If the monthly option looks generous, and it often does for people in good health, keeping it can be worth more than the flexibility.
Frequently asked questions #
How do I handle a pension with no inflation adjustment? #
Convert it to today’s dollars before subtracting it. Divide the future payment by (1 + inflation) raised to the number of years until it starts, and remember it will keep losing value after payments begin. Many planners assume a fixed pension covers less of their spending each decade.
Should I take a lump sum or lifetime payments for FIRE? #
It depends on your health, your other income and how you feel about market risk. Lifetime payments provide a floor that makes the rest of your plan safer. A lump sum offers flexibility and an inheritance but shifts all the risk to you.
Can I use the 4% rule with a deferred pension? #
Not on your whole budget. Applying it to your post-pension gap alone understates what you need during the years before the pension starts. Split your plan into a bridge fund for the gap years and a core portfolio for the rest; see how to calculate your FIRE number for the basic formula.
Will my pension reduce my Social Security? #
Not anymore because of WEP or GPO. The Social Security Fairness Act repealed both, starting with benefits for months after December 2023. Your Social Security benefit is still based on your own earnings record, so years in a job that didn’t pay Social Security taxes don’t add to it.