What inflation does to money left in a current account
Nominal versus real returns, and why a balance that never falls can still lose ground.
The short answer
Money sitting in a current account that pays no interest keeps the same number on the statement and still loses value. Inflation raises the price of the things the money was being kept for, so the same balance buys less each year, and the shortfall compounds. At illustrative inflation of 2% to 6% a year, an untouched balance would give up somewhere between roughly a fifth and roughly two fifths of its purchasing power over a decade — a real loss that never appears as a debit anywhere.
Nominal return and real return
Two different numbers get called a return, and confusing them is what makes an idle balance look safe.
The nominal return is the change in the number of dollars. It is the rate an account advertises. A current account paying nothing has a nominal return of 0%: put in $5,000, come back in a year, and $5,000 is still there.
The real return is the change in what those dollars buy. It takes the nominal return and adjusts it for inflation — the general rise in prices across a basket of goods and services. Real return is the number that decides whether you can still afford the thing the money was for.
The relationship is a division rather than a subtraction. If the nominal rate is r and inflation is i, the real return is (1 + r) ÷ (1 + i) − 1. Subtracting inflation from the nominal rate gets close enough for most mental arithmetic. It flatters the result slightly where the account beats inflation, and slightly overstates the loss where inflation is ahead. At small rates the gap between the shortcut and the exact figure is a fraction of a percentage point; at larger rates it widens.
| Nominal rate on the account | Inflation | Approximate real return |
|---|---|---|
| 0% | 3% | −2.91% |
| 1% | 3% | −1.94% |
| 3% | 3% | 0% |
| 4% | 3% | +0.97% |
| 2% | 5% | −2.86% |
| 5% | 2% | +2.94% |
Two things stand out in that table. A positive nominal rate can still be a real loss — 2% in an account against 5% inflation leaves you behind. And the account paying nothing is not neutral. Its real return is negative by almost the full rate of inflation, every year, whether or not anyone notices.
How a balance loses ground in a year
Take one round number and one illustrative inflation rate: $6,000 held for twelve months, prices up 4% over that period, account paying 0%.
Start with what the money was for. Suppose $6,000 was set aside to cover a specific set of costs — a replacement car, a run of repairs, several months of essential outgoings. At the start of the year, $6,000 covered them exactly. A year later, the same set of costs is priced 4% higher: $6,000 × 1.04 = $6,240. The balance is still $6,000. You are $240 short of the thing you were saving for.
Run it the other way and you get the same fact in different units. The $6,000 you are holding, expressed in the buying power it had a year ago, is $6,000 ÷ 1.04 = $5,769. Roughly $230 of purchasing power has gone.
The two figures — $240 and $230 — are not a contradiction. One states the gap in next year's prices, the other states it in last year's. Both describe a single loss of about 4%. Whenever an inflation figure looks slightly off by a few percent, this is usually why: it matters which year's dollars the answer is quoted in.
Nothing on the statement records either number. There is no line labelled inflation, no fee, no notification. The balance is intact and the loss is real, which is exactly what makes it easy to leave in place for years.
The same sum over ten years
One year at a low rate is a rounding error to most households. The mechanism gets interesting because it compounds: each year's price rise applies to the already-raised prices, so the erosion accelerates in absolute terms even when the rate stays flat.
The table below takes $10,000 in an account paying no interest, and shows what it would still buy after various periods at three illustrative inflation rates. The arithmetic is simply $10,000 divided by (1 + inflation) raised to the power of the number of years held, with figures rounded to the nearest ten.
| Held for | At 2% inflation | At 4% inflation | At 6% inflation |
|---|---|---|---|
| 1 year | $9,800 | $9,620 | $9,430 |
| 3 years | $9,420 | $8,890 | $8,400 |
| 5 years | $9,060 | $8,220 | $7,470 |
| 10 years | $8,200 | $6,760 | $5,580 |
The spread across that bottom row is the point worth carrying away. The difference between a low-inflation decade and a high-inflation one, on identical money left completely alone, is the difference between keeping about four fifths of your buying power and keeping a little over half of it. Nobody made a bad decision to produce the right-hand column. The money simply sat still while prices did not.
A rough shortcut for the same idea: dividing 70 by the inflation rate gives an approximate number of years for purchasing power to halve. At 4%, that is around 17 or 18 years. At 7%, around 10. It is an approximation and it drifts at higher rates, but it is close enough to sanity-check a long horizon in your head.
Why an account paying nothing has a cost
Current accounts are usually designed around access rather than return. Money is available the same day, payments clear, cards work, and in many cases no monthly fee is charged. Interest is often zero or close to it.
That combination is genuinely useful, and it is not free. The cost is paid in real terms rather than in fees, which is why it is easy to miss. A balance kept in a 0% account during a period of 3% inflation is paying something in the order of 3% a year for the convenience of instant access — invisibly, and on every dollar, including the dollars that were never going to be spent this year.
That framing turns the question from "am I losing money?" into a comparison, which is more useful. Two accounts, one paying nothing and one paying an illustrative 3%, holding $8,000 for a year, differ by $240 in nominal terms. Inflation applies equally to both, so the $240 is the whole of the difference between them. The gap between two accounts is a nominal question. Whether either of them keeps up with prices is a real one. Both are worth asking, and they have different answers.
It is also worth separating the money by job. A float that covers this month's bills is doing work no interest rate can replace; the sum it holds is small and the period is short, so the real cost is small too. A balance that has quietly grown over several years, and that nobody has looked at recently, is where the arithmetic above starts to bite.
Why the loss is hard to see
Several things conspire to hide a real loss.
- Statements are nominal. Every figure a bank shows is in current dollars. There is no field for purchasing power, and no alert when it falls.
- The number never goes down. Loss aversion keys on falling balances. A flat balance reads as "no change" even when the world around it has moved.
- Prices move unevenly. Headline inflation is an average across a basket. Rent, energy, food and insurance can each move at very different rates, so the felt experience rarely matches the published figure.
- Your basket is not the basket. A household with a fixed housing cost and high grocery spend experiences a different personal inflation rate from one with a rising rent. The published average is a reasonable proxy, not a personal measurement.
- Interest is taxed on the nominal figure. Where savings interest is taxable, the tax is generally calculated on the nominal interest received, not on the real return. That can leave an account with a positive nominal rate and a negative real one after tax. The rules and thresholds vary by jurisdiction and by circumstances.
What this does not imply
The arithmetic is straightforward, and the conclusions people draw from it often overshoot. A few things it does not establish.
It does not mean cash is a mistake. Money that might be needed next week has to be reachable next week. Certainty and access have value that no real-return calculation captures, and a small real cost on a small balance for a short period is often a sensible price for them.
It does not mean higher-return options are equivalent. Accounts differ in access, notice periods, rate structure and deposit protection. Investments carry the possibility of losing money in nominal terms too, which is a different risk from slow real erosion. Comparing a 0% current account with anything else means comparing those features, not only the headline rates.
It does not mean the past predicts the next decade. Inflation rates vary widely across periods and countries. The 2%, 4% and 6% columns above are illustrative brackets for showing how the mechanism behaves, not a forecast of anything.
It does not settle anyone's individual position. Tax treatment, existing debt, income stability and what the money is actually for all change the answer. Anything specific is a conversation for a qualified professional who knows your situation.
What this means in practice
The single idea worth keeping is the distinction between the two returns. The nominal one is printed on the statement. The real one — nominal minus inflation, roughly — is the one that determines whether a balance still covers what it was meant to cover. A balance that never falls can still be losing ground, steadily and without notification.
From there, a few considerations tend to follow rather than a course of action.
- How much of the balance is a working float for near-term payments, and how much has simply accumulated and stayed?
- What nominal rate, if any, is the account actually paying — and when was that last checked, given introductory rates expire?
- Over what horizon is the money likely to be needed? A few weeks makes the real cost trivial. Several years makes it the main event.
- Which prices matter most in your own spending, since those, not the headline average, are the ones eroding this particular balance?
None of that produces a number that applies to everyone, and the honest version of this explainer stops short of pretending otherwise. What it does provide is the arithmetic: multiply by (1 + inflation) to see what a future cost becomes, divide by it to see what today's balance is worth in yesterday's money, and compare accounts on their nominal difference while judging all of them against prices. That is enough to see clearly what an idle balance is doing, which is a different thing from knowing what to do about it.
