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FIRE Calculator for Spain: Calculate When You Can Retire Early

A complete guide to financial independence in Spain: how Arfin's FIRE calculator works, key variables, example scenarios, and common mistakes.

March 16, 202617 min

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Retiring at 67 is not mandatory. It is simply what most people assume.

More and more people in Spain are discovering the FIRE movement (Financial Independence, Retire Early) and asking themselves: how much do I need to stop depending on a paycheck? Is it possible on Spanish salaries? What role does the public pension play?

The short answer: yes, it is possible. But generic FIRE calculators, designed for the American market, can give you misleading results if you live in Spain. The tax system is different, the healthcare system is different, and the public pension system is different.

In this guide, we will cover:

Let's get into it.

What is the FIRE movement

FIRE stands for Financial Independence, Retire Early. The core idea is straightforward:

  1. Save and invest a high percentage of your income.
  2. Build a portfolio large enough to cover your annual expenses indefinitely.
  3. Work becomes optional. You do not have to quit, but you can.

It is not about living like a monk or becoming a millionaire. It is about reaching the point where your investments generate enough to sustain your lifestyle.

The fundamental calculation is:

Required portfolio = Annual expenses / Safe withdrawal rate

If you spend 24,000 EUR per year and use a 4% withdrawal rate, you need 600,000 EUR invested. At 3.5%, you need 685,000 EUR.

The movement originated in the United States with books like Your Money or Your Life and blogs like Mr. Money Mustache. But the principles are universal. What changes are the details: taxes, healthcare, pensions, and cost of living.

Why generic FIRE calculators do not work for Spain

Most FIRE calculators you find online are designed for the American context. This creates three significant problems if you live in Spain.

1. Investment taxes are different

In the United States, long-term capital gains are taxed at 0% to 20%, and there are powerful tax-advantaged accounts (401k, Roth IRA) that allow you to defer or eliminate taxes entirely.

In Spain, capital gains and savings income are taxed under the savings base (base del ahorro) with progressive brackets:

There is no equivalent to the Roth IRA. Spanish pension plans have a limited deduction (1,500 EUR/year) and are taxed as employment income when you withdraw, which can actually be worse.

If a calculator assumes 0% tax on your withdrawals, it will overestimate your purchasing power by 19-27%.

2. There is a public pension system (Seguridad Social)

The Spanish pension system is one of the most generous in Europe. If you have contributed for 15 years or more, you are entitled to a contributory pension. With 37 years of contributions, you can receive 100% of your regulatory base.

This means that from age 65-67 onward, your FIRE portfolio requirements drop significantly. American calculators do not account for this cushion because Social Security in the US is far more modest.

3. Public healthcare changes the equation

In the United States, health insurance is one of the largest expenses in early retirement. It can easily cost 500-1,500 USD per month per person.

In Spain, you have access to the public healthcare system as long as you are a resident. Even if you stop working, you can maintain coverage through a special agreement with Social Security (convenio especial) for roughly 60-300 EUR/month depending on age and contribution base.

This dramatically reduces projected expenses. A calculator that includes 15,000 USD per year in health insurance will give you an unnecessarily high FIRE number.

The bottom line

If you use a generic calculator without adjusting for these factors, you will likely:

You need a calculator that understands the Spanish context. That is exactly what we built at Arfin.

The key variables for FIRE in Spain

Before you start playing with any calculator, you need to understand the variables that truly matter. Let's go through each one.

Savings rate

This is the percentage of your net income that you invest. It is, by far, the most important variable for reaching FIRE.

The savings rate matters more than investment returns, especially in the early years. You can control it directly, unlike markets.

For most people in Spain earning an average salary (25,000-35,000 EUR gross), a savings rate of 20-40% is ambitious but achievable if you optimize expenses like housing, transportation, and leisure.

Expected investment returns

A diversified global equity portfolio (such as an MSCI World index) has historically returned 7-8% nominally per year over long periods. Adjusted for inflation, that comes down to 4-5% real.

For a FIRE calculator, it is prudent to use a 5-7% nominal return or a 3-5% real return. Being too optimistic (10%+) can lead you to retire with an insufficient portfolio.

Tax drag

Every time you sell positions or receive dividends, you pay taxes. This tax drag reduces your effective returns.

In Spain, if your portfolio generates 7% gross and you pay an average 21% on realized gains, your net return drops to approximately 5.5%. This varies depending on:

Using accumulating index funds and minimizing sales is the most tax-efficient strategy in Spain.

Withdrawal rate

The famous 4% rule comes from the Trinity Study, which analyzed American portfolios from 1926 to 1995 and concluded that withdrawing 4% annually (adjusted for inflation) had a 95% chance of not depleting the portfolio over 30 years.

But there are nuances for Europe:

That is why many European financial planners recommend using 3.5% or even 3% as a safe withdrawal rate. It is more conservative, but it gives you a significantly larger margin of safety.

At 3.5%, you need roughly 28.5 times your annual expenses invested. At 4%, you need 25 times.

Inflation

Inflation erodes the purchasing power of your portfolio. If you spend 24,000 EUR per year today, in 20 years you will need roughly 35,000 EUR to maintain the same standard of living (assuming 2% average inflation).

A good FIRE calculator adjusts all values for inflation. If it does not, you are looking at deceptively optimistic numbers.

In Spain, historical average inflation has been between 2% and 3%. After the 2022-2023 spike, it has stabilized again around 2-3%.

Public pension as an offset variable

If you have contributed enough to the Social Security system, from age 65-67 onward you will receive a public pension. This means your FIRE portfolio does not need to cover expenses for life, but only the gap between your early retirement and when the pension starts.

From that point on, the pension covers part (or all) of your expenses, and your portfolio can supplement the difference.

This is something American FIRE calculators simply do not model. A calculator designed for Spain should allow you to include the estimated public pension as future income.

How Arfin's FIRE calculator works

The Arfin FIRE calculator is designed specifically for European investors, with a special focus on Spanish taxation. Here is what sets it apart from generic calculators.

The inputs you provide

The Monte Carlo simulation

This is where Arfin differs from simple calculators that use a straight line.

In reality, investments do not grow 7% every year. Some years they go up 25%, others they drop 15%. The order in which the ups and downs occur matters enormously, especially during the withdrawal phase (known as sequence of returns risk).

Arfin's calculator runs a Monte Carlo simulation with thousands of possible scenarios. In each scenario, annual returns are randomly generated following a statistical distribution based on historical data.

The result is not a single number, but a probability distribution:

This gives you a far more realistic picture than a simple linear projection. You can see how robust your plan is against market volatility.

What you see in the results

You can adjust the variables in real time and see how results change instantly. What happens if you save 200 EUR more per month? What if returns are only 5%? What if you retire 3 years later? The calculator lets you experiment with all these scenarios.

Example scenarios

Let's look at two concrete cases to make the numbers tangible.

Scenario 1: Single person earning 40,000 EUR gross

With these inputs:

Using Arfin's Monte Carlo simulation:

If this person can increase savings to 1,200 EUR/month (by reducing expenses or increasing income), the median age drops to 44-46, with a much higher success probability.

From age 67, the public pension of 1,200 EUR/month would cover 75% of expenses, allowing a dramatic reduction in portfolio withdrawals (or even letting the portfolio continue to grow).

Scenario 2: Couple earning 70,000 EUR gross combined

With these inputs:

Using the Monte Carlo simulation:

If the couple can increase savings to 2,000 EUR/month (for example, through gradual salary increases), the median age drops to 49-51.

A strategy many FIRE couples use: one person continues working part-time or freelancing while the other "retires." This reduces the effective withdrawal rate and dramatically increases the success probability.

Lessons from these scenarios

Where to invest for FIRE in Spain

Having a calculator is great, but it is useless if you are not investing. Here are the most common options for FIRE seekers in Spain.

Index funds and ETFs (the foundation)

The most popular strategy in the FIRE community is investing in low-cost global index funds. The idea: buy the entire world market with a single position and let compound interest do its work.

Popular ETFs for FIRE investors in Spain:

All of these are accumulating ETFs, meaning they reinvest dividends automatically, avoiding the taxable event of receiving dividend payments.

Where to buy these ETFs

You need a broker. The most popular options for investors in Spain:

Many FIRE investors in Spain use both: Trade Republic for automatic monthly DCA and DEGIRO for one-off trades or access to more markets.

Pension plans (with caution)

Spanish pension plans allow you to deduct up to 1,500 EUR annually from your tax base. It sounds attractive, but there is a catch: when you withdraw, the money is taxed as employment income, with marginal rates that can reach 47%.

For the FIRE community, pension plans only make sense if:

They should not be the foundation of your FIRE strategy, but rather a tactical complement.

Roboadvisors

Options like Indexa Capital, inbestMe, or MyInvestor Cartera Indexada offer automated management of index fund portfolios. Their advantages:

The downside: higher fees than doing it yourself (0.4-0.7% total vs 0.20% for an ETF).

For those who do not want to deal with any complexity, they are a solid option. For those who want to optimize every basis point of cost, direct ETFs are better.

Common FIRE mistakes in Spain

After analyzing hundreds of FIRE plans, these are the mistakes we see most often.

1. Ignoring taxes on withdrawals

This is the number one mistake. If you calculate that you need 600,000 EUR assuming you will withdraw 24,000 EUR and receive it all, you are wrong. Part of each withdrawal will be capital gains and will be taxed at 19-27%.

The fix: calculate your FIRE target in gross terms, not net. Or better yet, use a calculator that does it for you.

2. Forgetting about inflation

"I need 20,000 EUR per year" sounds reasonable today. But if you plan to retire in 20 years, those 20,000 EUR will be equivalent to roughly 13,000 EUR in today's money (at 2.5% inflation). Your target must grow with inflation.

3. Being too optimistic about returns

Using 10% or 12% nominal returns because "the S&P 500 has done that over the last 10 years" is dangerous. Past performance does not guarantee future results, and current valuations suggest lower expected returns for the next decade.

Be conservative: use 5-7% nominal or 3-5% real. If the market does better, it will be a pleasant surprise.

4. Not accounting for long-term healthcare costs

Although Spain has public healthcare, there are expenses that can increase with age: dental work, optical care, physiotherapy, possible supplementary private insurance. Include a margin in your projected expenses.

5. Trusting the 4% rule without nuance

The 4% rule is based on historical US data (1926-1995), an exceptionally good period for American equities. There is no guarantee that the next 50 years will be the same, especially for a globally diversified portfolio.

Using 3.5% gives you a cushion that can be the difference between a plan that works and one that leaves you without money at 75.

6. Not considering the public pension

Many in the FIRE community say "I am not counting on the pension." It is prudent to be conservative, but ignoring it entirely can make you work extra years unnecessarily. Even if the pension is reduced in the future, it is unlikely to disappear.

The most sensible approach: include it in your calculations, but with a 20-30% discount on what you would be entitled to today. That covers a potential future cut.

7. Underestimating the "extras"

Vacations, car repairs, home maintenance, gifts, emergencies. Your base monthly budget does not cover these irregular expenses. Add a 10-15% margin on top of your estimated monthly expenses.

Put the numbers to work

Planning for financial independence is one of the most transformative decisions you can make. Not because you will quit your job tomorrow, but because it gives you clarity about your situation, your options, and your future.

But plans only work if they are based on realistic numbers. And numbers are only useful if they account for your context: Spanish taxes, the public pension, healthcare, European inflation.

Try Arfin's FIRE calculator

The Arfin FIRE calculator is designed for investors in Spain and Europe. It includes:

If you do not have a broker yet, you can open a DEGIRO account or open a Trade Republic account to start investing today.

And if you already invest but are not sure when you could reach financial independence, Arfin helps you see it clearly.

Sign up for Arfin for free and start calculating your path to FIRE.

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