Savers in different countries receive very different returns on essentially identical products. The gap has little to do with how generous local banks feel and a great deal to do with monetary conditions.
The policy rate sets the floor
A bank can deposit surplus funds with its central bank at the official rate. That rate is the return available without lending to anyone, so it anchors what banks will pay savers.
Policy rates differ between countries because each central bank responds to its own inflation and employment conditions. Those conditions are rarely synchronised.
A country fighting rapid price increases will hold rates high, and its savers benefit. One holding rates low to support demand offers savers very little.
Why high rates do not mean high real returns
A high nominal deposit rate in a high-inflation country may still lose purchasing power. The comparison that matters is the rate net of local price increases.
Currency movement compounds this for anyone comparing across borders. A high-rate currency frequently weakens over time, offsetting the interest advantage.
This relationship is why simply moving savings to the highest-rate country rarely produces the expected gain. The market prices the difference into the exchange rate.
How competition for deposits changes the offer
Banks pay for deposits because deposits fund lending. Where loan demand is strong relative to available funding, banks compete harder and rates rise.
Where banks are already flush with deposits, they have little reason to pay more. Large retail banks in such conditions often pay well below the policy rate.
Digital banks without branch networks typically pay more, since their cost of serving an account is lower. The gap between the best and the average offer is often wide.
What deposit insurance changes
Most countries guarantee deposits up to a limit through a national scheme. The guarantee lets a saver treat all covered banks as equivalently safe.
Once safety is equalised, competition happens on rate alone, which narrows the gap between institutions. Without such a scheme, savers demand extra return from weaker banks.
Coverage limits, funding arrangements and which products qualify vary considerably by jurisdiction and are periodically revised. A foreign branch may sit under a different scheme than it appears to.
Why cross-border saving is harder than it looks
Opening an account abroad generally requires residency, local identification or a tax number. Access is the practical barrier rather than the interest rate.
Interest earned abroad may face withholding at source and remains reportable at home. Treaty relief exists in many cases but requires paperwork before the payment, not after.
The rate difference must therefore cover conversion costs, administration and currency risk before it is a genuine advantage. Frequently it does not.