Why the money in your bank loses value: real return versus inflation

The money you keep in the bank does not shrink in your account, but it buys less every year. With Spain's flash CPI for September 2026 at 4.9% (INE) and savings accounts with no payroll requirement paying around 3% TAE (the annual equivalent rate) before tax, bank savings now have a negative real return: over one year, €20,000 in an account at 3.04% TAE loses about €465 of purchasing power.

This guide explains how to calculate that loss, how much it can add up to over 5, 10 and 20 years, why banks do not make up for it and what options exist to reduce it, each with its own risks.

What it means for money to lose value when your balance does not fall

Your balance is a nominal figure: €20,000 is still €20,000 a year from now. What changes is what you can buy with it. If prices rise by 4.9%, something that costs €1,000 today will cost €1,049 in twelve months, and your €20,000 will only cover what would be worth about €19,066 today.

That is how inflation works: it does not destroy your capital, it erodes its purchasing power. So the useful question is not how much the bank pays you, but how much you are left with after tax and rising prices.

What banks pay and how high inflation is today

These are the reference figures at the start of October 2026. Banks change their offers often, so check the terms before you sign up.

Even the highest offer, which requires payroll, direct debits and card spending, has a rate that lasts one year and a low balance cap. After the 19% withholding tax, a 5.10% gross rate becomes 4.13% net, still below 4.9% inflation. You can see the full list in our comparison of savings accounts.

How to calculate the real return on your savings

The real return is what your money earns once tax and inflation are deducted. The exact formula is:

Real return = (1 + net return) / (1 + inflation) − 1

A quick approximation is to subtract: net return minus inflation. Applied to an account at 3.04% TAE:

1. Gross interest: 3.04%.
2. After the 19% withholding tax: 3.04% × 0.81 = 2.46% net.
3. After 4.9% inflation: (1.0246 / 1.049) − 1 = −2.32% real return.

Example with €20,000 over one year

Assumptions: 19% withholding tax on interest and constant inflation of 4.9% over the next twelve months. This is a calculation assumption, not a forecast.

Two conclusions: a savings account cuts the loss roughly in half compared with a non-interest account, but does not eliminate it. To break even against 4.9% inflation after tax, an account would have to pay around 6.05% TAE gross.

How much value is lost over the years

The effect of one year looks small. What matters is how it accumulates, like compound interest but in reverse. The table shows how much purchasing power, in today's euros, €100,000 with no interest would keep for each average annual inflation rate.

Inflation does not stay constant and September's 4.9% may not last; we include it as a high scenario. With 2% inflation, the ECB's target, idle money loses a third of its purchasing power in 20 years. At 3%, it takes about 23 years to lose half. At 4.9%, about 14 and a half years.

Your personal inflation may be different

The CPI measures an average basket. If your spending is concentrated on rent, energy or food, your real inflation may be higher or lower than the official figure. It is worth bearing in mind when you work out how much you need, for example, to plan for financial independence.

Why the bank does not make up for inflation

When the ECB raises rates, banks have room to pay more on deposits, but they are not obliged to pass it on. The large traditional banks still do not offer competitive savings accounts; the best terms come from neobanks, brokers and institutions trying to win new customers, and they tend to be temporary or have balance caps.

The rate on an instant-access account can also be changed with advance notice. And the advertised TAE is gross: the tax authorities tax interest in the savings base of Spanish income tax (19% up to €6,000, 21% up to €50,000, 23% up to €200,000, 27% up to €300,000 and 30% above that).

Options to reduce the loss of purchasing power

There is no single option that suits every case. All of them trade expected return for liquidity, stability or risk, and none ensures you will beat inflation.

How much money should stay in the bank and how much should not

Money losing value in the bank does not mean you should withdraw all of it. A savings account is the right place for your emergency fund, usually 3 to 6 months of expenses, and for money you will need in the coming weeks or months. There, availability matters most, and the real loss is the price of having immediate liquidity.

The problem appears when savings you will not touch for years are also sitting in the account. That part takes a cumulative loss with nothing in return. If you also hold more than €100,000 in a single institution, see the risks of going over the deposit guarantee limit (in Spanish).

How to split your savings between liquidity, short term and long term depends on your income, your spending, your time horizon and how much fluctuation you can tolerate. If you need personalised advice, speak to an authorised financial adviser. You can also explore the investment strategies we cover on the blog (in Spanish).

Invoice financing: an option for short- and medium-term savings

One option for the part of your savings that you do not need right away is crowdfactoring. At Inversa, the investor finances invoices and promissory notes already issued by SMEs and self-employed workers who want to get paid sooner, and recovers the capital when the debtor pays at maturity.

• Terms: from 30 to 180 days.
• Minimum amount: from €20, which lets you spread your money across many invoices.
• Fees for the investor: 0%.
• Custody: funds are held in segregated accounts in each client's name at Paymatico Payment Institution, a payment institution registered with the Bank of Spain under number 6861.

What the risks are

Zero risk does not exist in any investment. Here the risk is specific: the company that owes the payment may not pay, may pay late or may dispute the invoice. Inversa is not a credit institution and is not part of any guarantee fund, so, unlike a deposit, there is no equivalent coverage. Liquidity arrives at the maturity of each invoice and, before that, only if another investor buys your position on the secondary market.

That is why it makes sense to spread the investment across many invoices and different debtors, and not to put your emergency fund into this product.

Common mistakes when measuring what your savings earn

• Looking only at the TAE. The return that matters is the real one: net of tax and inflation.
• Trusting promotional rates. A 3.51% rate for four months followed by 1.15% earns less over the year than a stable account at 2.50%.
• Ignoring the balance cap. Above the interest-bearing limit, your money earns less or nothing.
• Waiting for rates to rise further. Nobody knows what the ECB will decide at its meeting on 29 October; betting everything on a single scenario is a risk decision, even if it looks like the conservative option.

Frequently asked questions

Does the money I keep in the bank lose value?

It loses purchasing power whenever inflation exceeds the net return your account pays. In October 2026, with flash CPI at 4.9% and the best unconditional accounts at around 3% TAE gross, that is the case in every example we reviewed.

How long does it take for money to lose half its value?

With constant inflation of 2%, about 35 years; at 3%, about 23 years; at 4.9%, about 14 and a half years. These figures assume no interest. Any net interest lengthens that period.

How do you calculate the real return on an account?

Subtract tax from the gross TAE to get the net return, then compare it with inflation using the formula (1 + net return) / (1 + inflation) − 1. If the result is negative, your money buys less than it did a year ago.

Does an ECB rate rise solve the problem?

It helps, because it gives banks room to pay more, but it does not oblige them to. Also, the ECB raises rates precisely because inflation is high, and that increase tends to reach savers late and only in part.

Should I take all my money out of the bank?

No. Money you need to have available immediately should be in an accessible account. The question is how much of the savings you will not use in the short term is still there out of inertia rather than by decision.