Money, Explained From the Inside

Tools / Save & grow / Chapter 2 · The Quiet Tax

The quiet tax

Inflation never sends a bill. It makes each unit of money buy a little less every year. Compare idle cash with money that earns a return.

1 · The idea

Purchasing power and real return

Prices rise by π each year, so money buys 1/(1 + π) as much a year later. The real return is not return minus inflation: it is the ratio of growth to price rises.

The formula

Buying power = M ÷ (1 + π)^t Real return = (1 + r) ÷ (1 + π) − 1

M
amount today
π
inflation per year
r
nominal return per year
t
years

2 · A worked example

$10,000 left idle for 20 years at 3% inflation buys what $5,537 buys today: 45% of its buying power gone. At a 5% return, the real return is 1.94% and it ends at $14,691 in today’s money.

3 · Now use your own numbers

Change anything. The result updates instantly.

Try an example
Idle cash will buy only
$5,53745% of its purchasing power is gone
To keep today’s buying power you will need
$18,061
Something costing 100 today costs
181
Real return (after inflation)
1.94%Not return minus inflation: (1 + return) ÷ (1 + inflation) − 1.
If invested: value in today’s money
$14,691
05k10k15k20k036912151820
Years on the horizontal axis.
  • Idle cash, buying power
  • Invested, buying power

What this means

The quiet tax is paid by anyone who holds more cash than they need, for longer than they need. A buffer is not wasted, but a pile far beyond it is slowly shrinking.

The return you actually keep is the real return. When inflation is high, a headline “5%” can be close to nothing.

Illustrative, not personal advice. Inspired by Chapter 2 · The Quiet Tax of Money, Explained From the Inside. Your figures stay in this browser. Real products add terms, taxes and conditions that this simple model leaves out.

4 · Take care

What this tool can’t see

  • Your own inflation differs from the headline figure; costs such as housing or education can rise faster.
  • Cash is the right home for a buffer, but not for money you will not need for many years.

5 · Go further

Where this fits

Private to this device. Nothing is sent anywhere.

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