Is Your 'Best Buy' Savings Account Actually Losing You Money? The Real Return Deep Dive

Headline savings rates look generous right now, but once you strip out inflation and tax, the "best buy" account you switched to six months ago may already be losing you money in real terms. Here's how to actually check.

The headline rates

As of late July 2026, the highest easy-access savings rate is 5.00% AER from Revolut and LemFi, once bonuses are included. Tembo Money pays 4.55% AER and Plum 4.52% AER, both bonus-inclusive. Savers willing to lock money away for five years can currently secure 4.94% AER guaranteed, while shorter fixed terms range from around 4.62% (Kent Reliance, 1 year) to 4.71% (2 years).

Why the headline rate is often a mirage

Many of these top rates rely on temporary bonuses. LemFi's rate includes a 1.89% bonus for six months, after which it drops to 3.04% AER. Revolut's bonus applies until 4 December 2026 and only on balances up to £25,000, with a lower 2.90% AER paid above that threshold. Once these bonuses expire, real returns can flip from positive to negative almost overnight if you don't actively move your money again.

The actual maths

UK CPI inflation was 2.6% in the year to June 2026. A saver earning a 4.5% headline rate is earning roughly 1.9 percentage points above inflation before tax — a genuine real return, but a modest one. Once a bonus rate like LemFi's drops to 3.04%, the real return before tax shrinks to just 0.44 percentage points, and tax can erase it entirely for some savers.

Interest above your Personal Savings Allowance — £1,000 for basic-rate taxpayers, £500 for higher-rate, and £0 for additional-rate taxpayers — is taxed at your marginal income tax rate. For a higher-rate taxpayer with substantial savings outside an ISA, a 3.04% rate after 40% tax delivers an effective return of around 1.82% — below the 2.6% inflation rate, meaning the money is losing purchasing power in real terms despite the account technically paying "interest."

How to check your own real return

1. Find your account's current AER, not the rate advertised when you opened it — check whether any bonus period has already expired.
2. Subtract your marginal tax rate's bite, if the account sits outside an ISA and you're over your Personal Savings Allowance.
3. Subtract the current CPI rate (2.6% as of June 2026) from what's left.
4. If the result is negative, your money is losing value in real terms even though your balance is growing in cash terms.
5. Consider a Cash ISA to shelter interest from tax entirely, particularly if you're a higher or additional-rate taxpayer with savings likely to exceed your Personal Savings Allowance.

International comparison

The UK's Personal Savings Allowance has no direct US equivalent — American savers pay ordinary income tax on virtually all interest from the first dollar, though certain municipal bond interest is tax-exempt. Australia offers no blanket savings interest allowance either, taxing interest at marginal rates, which makes the UK's ISA wrapper comparatively generous by international standards for sheltering cash savings from tax.

Key Numbers

• 2.6% — UK CPI inflation, year to June 2026
• 5.00% AER — top bonus-inclusive easy-access rate, from Revolut and LemFi
• £1,000 / £500 / £0 — Personal Savings Allowance for basic, higher and additional-rate taxpayers

Sources

• Be Clever With Your Cash: The best easy-access savings accounts (July 2026)
• Moneyfacts: The Highest UK Savings Rates
• MoneyWeek: UK inflation slows to 2.6% in June
• GOV.UK: Personal Savings Allowance

Educational content only — not financial advice.