FIRE glossary: every term explained

The FIRE movement has built its own vocabulary, and most of it is used loosely. People argue about Lean FIRE and Fat FIRE without ever stating a number, quote the 4% rule as if it were a law, and use words like drawdown to mean two completely different things in the same paragraph. This glossary covers the whole vocabulary in one place, from the core arithmetic to the country-specific tax rules behind our 13 country calculators. Where a term is US-specific, we say so. Where the community genuinely disagrees about a definition, we say that too rather than pretending there is one answer.

Numbers

The 4% Rule

The best known rule of thumb in FIRE: withdraw 4% of your portfolio in the first year of retirement, then increase that cash amount by inflation every year afterwards, whatever the market does. It came out of William Bengen's 1994 research on historical US market data and was reinforced by the Trinity Study four years later. Two things are widely misunderstood. It is not 4% of your current balance each year, which would be a different and much safer rule. And it was tested over roughly 30 year retirements, not the 40 or 50 year horizons many FIRE plans assume. Treat it as a benchmark, not a guarantee, and see how sensitive the answer is on the 4% rule calculator.

A

Accumulation Phase

The years when you are adding money to your portfolio rather than taking it out. Contributions and compound growth both push the balance up, market falls are an opportunity because you are still buying, and the two levers that matter are your savings rate and the time you have left. It ends when you stop contributing, which under Coast FIRE happens long before you stop working. The distinction matters because the risks invert: during accumulation, volatility is mostly noise, while in the withdrawal phase the same volatility becomes sequence risk. Most of the arithmetic on this site, including the Coast FIRE calculator, models the accumulation phase.

Asset Allocation

How your portfolio is split between asset classes, typically shares, bonds and cash. It is usually written as a pair of percentages, so 80/20 means 80% shares and 20% bonds. Allocation drives both your expected return and how far the portfolio falls in a bad year, which is why it matters far more to a FIRE plan than picking clever individual funds. Many people hold a high share allocation while accumulating and add bonds or cash in the years before they start withdrawing, precisely to soften sequence of returns risk. There is no single correct split, and sensible planners disagree sharply about how much belongs in bonds.

B

Barista FIRE

A halfway state where your portfolio covers most of your living costs and part-time work covers the rest. The name comes from the American idea of taking a coffee-shop job that carries health insurance, which is the part that makes it specifically attractive to US early retirees. Outside the US that health cover angle largely disappears, and Barista FIRE simply means a smaller portfolio plus a smaller job. It cuts your target because you are no longer asking the portfolio to fund everything, and it cuts the psychological jump too, since you are not stopping work in one step. Read what Barista FIRE is, or run the numbers on the Barista FIRE calculator.

Box 3

The Dutch tax box covering savings and investments. It taxes what you own rather than what you earn: the tax office applies a deemed return to your assets and taxes that figure. For 2026 the deemed return on investments is 6.00%, the box 3 rate is 36% and the tax free allowance is 59,357 euro per person, which works out at roughly 2.16% a year on investment value above the allowance, whether or not markets actually rose. If your real return was lower you can use the tegenbewijsregeling and be taxed on the actual figure instead. Pension and lijfrente capital sit outside box 3 entirely, which is why the pillar you hold money in matters so much. Netherlands-specific, and modelled in the Netherlands FIRE calculator.

Bridge Fund / Bridge Account

Money you can actually reach before your pension or retirement accounts unlock. If you stop work at 50 but your pension is locked until 57 or 60, the bridge fund pays for those years. It normally lives in a taxable brokerage account, an ISA in the UK, or a TFSA in Canada, weighted more towards cash and bonds than the rest of the portfolio because the spending date is close. Sizing it is simple: annual spending multiplied by the number of bridge years, plus a margin for bad markets. Getting it wrong is the most common structural error in early retirement plans, because people hit their total number while holding nearly all of it somewhere they cannot legally touch. Worked through in the retire at 50 guide.

Bucket Strategy

A way of organising a retirement portfolio by when you will spend the money rather than by asset class alone. A common setup holds one to three years of spending in cash, several more years in bonds, and everything else in shares, refilling the cash bucket from the longer buckets when markets allow rather than on a fixed schedule. The appeal is behavioural as much as mathematical: you can point at the cash and know you will not be forced to sell shares during a crash. Critics argue it is an asset allocation in disguise with extra bookkeeping. It is compared against the alternatives in FIRE withdrawal strategies.

C

Chubby FIRE

An informal tier sitting between an ordinary FIRE target and Fat FIRE: comfortable rather than lavish, with room for travel and a decent house but not unlimited spending. There is no agreed threshold, and this is a term where you should assume nothing about what someone means until they state a number. In practice people use it for spending above a typical middle-class budget but below the levels usually described as Fat FIRE, and the boundary moves with country and city. Because the label is a matter of taste rather than arithmetic, the useful move is to ignore it and calculate against your own budget with the FIRE number calculator.

Coast FIRE

The point at which your invested money is already large enough to grow into your full FIRE number by your target retirement age with no further contributions. You keep working, but only to pay today's bills, because the retirement saving is finished. It is the earliest FIRE milestone to reach and the one that changes your life soonest, since it removes the pressure to maximise income and lets you take the lower paid job or the sabbatical. The arithmetic depends heavily on your assumed real return and how many years of compounding remain, so test more than one return. Read what Coast FIRE is, find your figure on the Coast FIRE calculator, or see the targets age by age.

Compound Growth

Growth on your growth. Each year's return is calculated on a balance that already includes previous returns, so the balance curves upward instead of climbing in a straight line. It is the entire engine behind Coast FIRE: money invested at 25 has forty years of compounding ahead of it, which is why an early contribution is worth several times a later one of the same size. The effect looks unimpressive for the first decade and dramatic after that, which is also why people give up too early. Small differences in the assumed rate matter enormously over long periods, so never build a plan on a single optimistic return figure.

Cost of Delay

What waiting costs, expressed in money rather than regret. It is the gap between the final balance you would reach starting now and the balance you would reach starting later, and it grows faster than the delay itself because the years you lose are the ones carrying the most compounding. Put bluntly, postponing by five years does not cost you five years of contributions. It costs you five years of contributions plus all the growth those contributions would have earned for the rest of your life. This is the strongest argument for starting badly rather than starting late, and you can see it directly in the Coast FIRE by age table, where the target rises steeply with every year you wait.

D

Deemed Disposal

An Irish rule that dominates FIRE conversations there. Under Finance Act 2006, units in an investment undertaking, which covers most funds and ETFs, are treated as sold at the end of every eight year period after you acquire them, and tax is charged on the paper gain even though you sold nothing. The exit tax rate for chargeable events on or after 1 January 2026 is 38%, reduced from 41%. Tax already paid is offset against tax due on a later chargeable event, so it is a timing problem rather than double taxation, but across a long accumulation it strips compounding out of the plan. Ireland-specific, with no equivalent in the UK or US, and covered in the Ireland FIRE calculator.

Dollar Cost Averaging

Be careful here, because the term carries two different meanings. In everyday use it means investing a fixed amount on a fixed schedule, which is what a monthly salary contribution does automatically. In academic and adviser use it means deliberately spreading an existing lump sum over several months instead of investing it all at once, which historically has usually produced a lower expected result than investing immediately, though it does reduce the pain of unlucky timing. Both are defensible, they are simply not the same thing. Whenever someone claims dollar cost averaging beats or loses to lump sum investing, check which of the two definitions they are using before agreeing.

Drawdown

Another word with two meanings that regularly get mixed up. In investment terms, a drawdown is the fall from a portfolio's peak to its lowest point before it recovers, quoted as a percentage, so a 40% drawdown means the balance dropped 40% from its high. In UK pension terms, drawdown means leaving your pension invested and taking income from it rather than buying an annuity. Both matter to FIRE planning and both often appear in the same paragraph. Read the context: percentages usually mean the first, pension rules usually mean the second. The mechanics of taking income are compared in FIRE withdrawal strategies.

E

Expense Ratio

The annual cost of owning a fund, quoted as a percentage of the amount invested and deducted from the fund's value rather than billed to you, so most people never see it leave. In the UK the same thing usually appears as the ongoing charges figure, or OCF. It sounds trivial and is not. Over a thirty or forty year accumulation the difference between 0.05% and 0.75% compounds into a meaningful share of your final balance, and unlike returns it is one of the very few variables you fully control. Fees are the main reason most FIRE portfolios are built from broad index funds rather than actively managed ones.

F

Fat FIRE

Financial independence at a comfortable or high level of spending, without the frugality other versions assume. Because the target scales with spending, Fat FIRE numbers are large, and the path usually runs through high income rather than extreme saving, which is why business owners, senior professionals and people with equity compensation are so heavily represented. There is no official threshold and the figure people mean varies widely by country and city. What it is not is a different set of maths: the same safe withdrawal rate arithmetic applies, just with bigger inputs. Read what Fat FIRE is or use the Fat FIRE calculator.

Financial Independence

The state where your assets can cover your living costs indefinitely without you needing to work for money. It is the FI half of FIRE and, for many people, the half that actually matters, because the retire-early part is optional. Independence is a threshold, not a lifestyle: reaching it does not oblige you to quit, and plenty of people carry on in the same job with an entirely different attitude to it. It is measured against your own spending rather than your income, which is why two people on identical salaries can be decades apart. The FIRE movement guide covers the wider idea, and the early retirement calculator turns your numbers into a date.

FIRE

Financial Independence, Retire Early. It describes both a goal and a loose international community built around it. The mechanics are unglamorous: keep a large gap between what you earn and what you spend, invest the difference in low cost diversified funds, and stop working for money once the portfolio can support you. The ideas predate the acronym and are usually traced to Vicki Robin and Joe Dominguez's book Your Money or Your Life and to the personal finance blogs that followed it. Usage varies more than newcomers expect: some people mean full early retirement, others mean simply having enough options that work becomes voluntary. Start with the FIRE movement guide.

FIRE Number

The portfolio value that funds your lifestyle indefinitely. The arithmetic is annual spending divided by your safe withdrawal rate, so $40,000 of spending divided by 4% gives $1,000,000, which is the same thing as 25 times annual spending. Everything difficult about it sits in the two inputs. Your real annual spending is usually higher than you think once tax, healthcare and irregular costs are included, and the withdrawal rate should reflect how long the money has to last. A state pension or social security starting later reduces the target, sometimes substantially. Get yours from the FIRE number calculator, or compare targets across systems on the country calculators.

G

Geographic Arbitrage

Earning or accumulating in a high cost location and spending in a cheaper one, which lowers your FIRE number without lowering your standard of living. It works domestically too, for example leaving an expensive capital for a cheaper region of the same country. The catches are real and routinely underestimated: visa and residency rules, tax residency in both the old and the new country, healthcare access, currency risk when your portfolio and your costs sit in different currencies, and the social cost of living far from the people you know. Our country calculators exist partly because the numbers change so much between systems.

Guardrails / Guyton-Klinger

A family of dynamic withdrawal approaches that adjust spending according to how the portfolio is doing, instead of raising withdrawals with inflation regardless. The best known version comes from decision rules published by Jonathan Guyton and William Klinger, which set upper and lower bands around your withdrawal rate: if the rate drifts above the upper guardrail you cut spending by a set percentage, and if it falls below the lower one you can give yourself a raise. Implementations differ, so always check the specific bands and cuts anyone is quoting. The trade-off is a higher starting withdrawal in exchange for genuinely accepting real spending cuts in bad years. Compared in FIRE withdrawal strategies.

I

Index Fund

A fund that holds the constituents of a market index rather than trying to beat it, available as either a mutual fund or an exchange traded fund. Because there is no research team to pay for, costs are low, and low costs are the most reliable advantage available to an ordinary investor. FIRE portfolios lean heavily on broad index funds covering entire markets and held for decades. One important caveat: the same fund can carry very different tax treatment in different countries, which is why Irish and German investors have to think much harder about fund structure than American ones do. See index funds for FIRE.

Inflation-Adjusted

A figure expressed in today's money, with the effect of inflation stripped out, so you can compare it directly to prices you understand now. It is the same idea as a real return, applied to balances and spending rather than to rates. The calculators on this site work in inflation-adjusted terms deliberately, because a target of 1.4 million in tomorrow's money tells you almost nothing, while knowing what it buys today tells you whether the plan is sensible. If a projection quotes a large future balance and does not state whether it is inflation-adjusted, assume it is not until you have checked.

L

Lean FIRE

Early retirement on a deliberately small budget, reached by cutting the spending side rather than raising the income side. Because the target is roughly spending times 25, a lean budget produces a dramatically smaller number and a much shorter timeline. The trade-off is fragility: a lean plan has little slack for a health problem, a family change, or an unexpectedly expensive decade, and the numbers quietly assume you will still be content on that budget in twenty years. Thresholds are cultural and vary a great deal between countries, so treat any quoted figure as local. Read what Lean FIRE is or use the Lean FIRE calculator.

M

Means Testing

Deciding whether someone gets a benefit, and how much, based on their income or assets. It matters to FIRE plans because a large portfolio can reduce or remove state support the plan quietly assumed. Whether it applies depends entirely on the country. The UK State Pension is based on National Insurance contributions and is not means tested. Ireland's State Pension (Contributory) is not means tested, while the Non-Contributory version is. Australia's Age Pension is subject to both an income test and an assets test, so a large superannuation balance can reduce it. Check the rules for your own system before counting a state pension in your target, starting from the country calculators.

N

Nominal Return

The headline return before inflation is taken out, which is what fund factsheets and news reports normally quote. It is the number that flatters. A 7% nominal return in a year when prices rose 3% has only made you about 3.9% better off in purchasing power terms. Nominal figures are perfectly fine for comparing two funds over the same period and actively misleading for long range planning, because a forty year projection at a nominal rate produces an enormous balance in money that buys much less than today's. Whenever you enter an assumption into a calculator, know which of the two it is asking for.

O

One More Year Syndrome

The habit of reaching your number and then working another year for safety, then another, indefinitely. It is a real pattern rather than a joke, and it comes from the fact that no plan ever feels finished: another year adds contributions, removes a year of withdrawals, and makes every projection look better. The cost is invisible on a spreadsheet, because it is time rather than money. The honest fix is to decide in advance what would make you stop, write those conditions down while you are still years away from them, and then treat hitting them as the decision rather than as the moment to reopen the argument.

P

Pension Access Age

The earliest age at which you can take money from a private or workplace pension. In the UK the normal minimum pension age is 55 and rises to 57 in 2028. Ireland allows benefits from a PRSA from 60, with occupational scheme normal retirement age typically between 60 and 70 and early retirement sometimes possible from 50 under scheme rules. Germany's statutory pension has its own ages and permanent reductions for drawing early. This age, rather than your FIRE number, is what forces most early retirees to build a bridge fund. Check yours on the country calculators, or read Coast FIRE in the UK for the British version.

Perpetual Withdrawal Rate

The withdrawal rate at which the portfolio's inflation-adjusted value is never permanently reduced, so in principle it could support your spending forever and still leave the capital intact. It is a stricter test than the 4% rule, which only asks that the money outlasts a fixed retirement length, so a perpetual rate always comes out lower. People reach for it when a retirement could run fifty years or more, or when leaving an estate matters to them. Treat any published figure with care, because it depends entirely on which market history, asset allocation and fee assumption produced it.

Preservation Age

The Australian term for the age at which superannuation becomes accessible. From the 2024 to 2025 financial year onwards it is 60 for everyone, having previously depended on date of birth. Reaching preservation age is not automatically the same as being free to spend the money, because access also requires meeting a condition of release, such as retiring. For an Australian FIRE plan this is the wall that determines how much has to be held outside super, since superannuation can easily be the largest single asset and completely unreachable at 45. Modelled in the Australia FIRE calculator.

Purchasing Power

What a sum of money actually buys, as opposed to how large the number looks. Inflation erodes it quietly: the same annual spending figure buys steadily less each decade, so a retirement plan that fixes spending in cash terms and never raises it is really a plan for a falling standard of living. Preserving purchasing power is why withdrawal rules increase the withdrawal with inflation, and why long horizon portfolios keep a heavy share allocation despite the volatility. Cash feels safe and loses purchasing power reliably. This becomes more pressing the longer the retirement, which the retire at 60 guide works through.

R

Real Return

The return after inflation, which is the only version that tells you whether you can buy more than before. The rough version is nominal return minus inflation. The precise version is one plus the nominal rate, divided by one plus the inflation rate, minus one. So 7% nominal with 3% inflation is about 3.9% real, not 4%. Every calculator on this site works in real terms so the answer arrives in today's money. A common conservative planning assumption for a diversified share portfolio is somewhere around 4% to 5% real, and it is worth running your plan a full percentage point lower as a stress test.

Rebalancing

Selling what has grown and buying what has lagged, to bring your portfolio back to its target asset allocation. Without it the best performing asset quietly takes over and your risk level drifts upward without you ever deciding to take more risk. Two common approaches: rebalance on a calendar, for example once a year, or rebalance whenever a holding drifts more than a set percentage from its target. Inside a tax-advantaged account this costs nothing in tax. Inside a taxable account, selling can trigger a bill, so many people rebalance by directing new contributions towards the underweight asset instead of selling anything.

Roth Conversion Ladder

A US strategy for reaching retirement money before 59½ without penalty. You move money from a traditional 401(k) or IRA into a Roth IRA, pay income tax on the converted amount in that year, then wait five tax years before withdrawing that converted amount penalty free. Repeat it annually and each year's conversion matures in turn, producing a rolling supply of accessible money. It usually works best in the low income years just after you stop working, when the tax cost of each conversion is smallest. It is US-specific and has no direct equivalent elsewhere. Full walkthrough in the Roth conversion ladder guide.

Rule of 55

A US provision letting you take money from the 401(k) or 403(b) of the employer you have just left, without the 10% early withdrawal penalty, provided you leave that job in or after the calendar year you turn 55. Income tax still applies. Two limits catch people out. It covers only the plan of the employer you separated from, not older plans and not IRAs, and rolling that balance into an IRA destroys the benefit entirely. Qualified public safety employees can use an equivalent from 50. The timing is explored in the retire at 55 guide.

S

Safe Withdrawal Rate

The percentage of your starting portfolio you can withdraw in the first year of retirement, increasing with inflation afterwards, without running out over your planned retirement length. It is the divisor in your FIRE number: a 4% rate means 25 times spending, 3.5% means about 28.6 times, and 3% means 33 times, so small changes move the target a long way. The right figure depends on retirement length, asset allocation, fees and how flexible you can be about spending in bad years. Nothing about it is guaranteed, because every published rate is derived from one particular slice of market history. Test yours on the 4% rule calculator.

Savings Rate

The share of your income you save and invest, and the single strongest predictor of how long the journey takes. It matters more than income, because it sets both how fast the portfolio grows and how small the lifestyle it eventually has to fund is. Definitions vary and people rarely say which they are using: gross or net income, whether an employer pension match counts, whether mortgage principal counts as saving. Pick one definition and stay consistent rather than arguing about whose is correct. The savings rate calculator turns your rate into a years-to-independence figure.

SEPP / 72(t)

Substantially equal periodic payments, a US route under section 72(t) of the tax code for taking money from an IRA or other retirement plan before 59½ without the 10% penalty. You commit to a fixed schedule of annual withdrawals calculated by one of three approved methods, and you have to keep taking them for five years or until you reach 59½, whichever is later. Breaking the schedule retroactively triggers penalties on everything already withdrawn, plus interest. That rigidity is why many early retirees prefer the Roth conversion ladder, or the rule of 55 where they qualify for it.

Sequence of Returns Risk

The risk that the order of your returns, not just their average, decides whether the money lasts. While you are withdrawing, a bad first few years force you to sell more units at low prices, and the portfolio may never recover even if the long run average turns out exactly as expected. Two retirees with identical average returns can end up in completely different places purely because of sequence. It is the reason safe withdrawal rates sit so far below expected returns, and the reason the first five years of retirement deserve cash buffers or flexible spending. Explained with a worked comparison in the sequence risk guide, and it bites hardest on the longest horizons, such as retiring at 40.

T

Taxable Brokerage Account

An ordinary investment account with no special tax treatment and, crucially, no age restrictions on withdrawals. Americans call it a taxable or brokerage account, the UK calls it a general investment account, and in countries such as Ireland and Germany it is simply where you invest once the sheltered options are used up. Because there is no lock on it, it is the natural home for a bridge fund. The cost is that dividends and gains are taxed as you go or when you sell, which is why the usual order is to fill tax-advantaged space first and hold in taxable accounts the money you will need early.

Tax-Advantaged Account

Any account that gets favourable tax treatment in exchange for rules about when or how the money comes out. The US has 401(k)s, IRAs and the HSA. The UK has ISAs and SIPPs, Canada the TFSA and RRSP, Australia superannuation, Ireland PRSAs and occupational schemes. Broadly they split into two kinds: those that are tax free and still accessible, such as an ISA or a TFSA, and those that are sheltered but locked until a pension access age. FIRE planning is largely the exercise of using both without stranding all your money in the locked kind. The HSA guide covers the American outlier that does both jobs at once.

Trinity Study

The 1998 paper by Philip Cooley, Carl Hubbard and Daniel Walz, professors at Trinity University in Texas, which tested how often various withdrawal rates survived historical US market periods across different portfolio mixes and retirement lengths. It did not invent the 4% figure, which came from William Bengen's earlier work, but it popularised the idea and gave the rule its usual name. Two limits are worth remembering when anyone cites it: it used US data only, which was one of the better performing markets of the twentieth century, and its longest tested period was thirty years, shorter than many FIRE retirements.

V

Vorabpauschale

A German advance lump sum that taxes the notional growth of an accumulating fund even when it distributes nothing. Under section 18 InvStG, the Basisertrag is the redemption price at the start of the year multiplied by 70% of the Basiszins, capped at the actual rise in value over the year plus any distributions. The Basiszins at 2 January 2026 was 3.20%, giving a Basisertrag of 2.24% of your January value. For an equity fund the Teilfreistellung exempts 30% of that, and the remainder is taxed at 25% Abgeltungsteuer plus the 5.5% solidarity surcharge. It is deemed received on the first working day of the following year. Germany-specific, and modelled in the Germany FIRE calculator.

W

Withdrawal Phase

Also called decumulation: the years when you are taking money out of the portfolio rather than adding to it. Everything inverts compared with the accumulation phase. Falling markets are now damaging rather than an opportunity, sequence of returns risk becomes the dominant threat, and the questions shift from how much to save to how much to take, from which account, in what order, and how to adjust when things go badly. Most people spend far more effort planning accumulation than withdrawal, despite the second phase being where plans actually fail. The options are compared in FIRE withdrawal strategies.