Free calculator · US & UK

Savings vs CD vs Treasury bills: where should cash sit?

The short answer: easy-access savings for money you might need, fixed terms for money with a date on it, and government bills when state tax or safety at size matters. This tool prices all three after tax at your own rates so the decision stops being a vibe.

Cash to place$20,000

Time horizon12 months

Easy-access savings rate3.80%

High-yield savings in the US, easy-access in the UK. Variable: it follows the central bank down, which is the hidden cost of flexibility in a rate-cut cycle.

Fixed-term rate (CD / fixed bond)4.20%

Locked for the term. You are paid to give up access; early exit usually costs months of interest.

Government bill rate (T-bill / gilt)4.00%

4 to 52 week government paper. In the US, T-bill interest is exempt from state income tax, which flatters the after-tax number in high-tax states.

Your tax rate on interest22%

US: your marginal federal (plus state, except on T-bills). UK: 0% inside the personal savings allowance or an ISA, then your income tax band.

Easy access ends at

$20,593

Fixed term ends at

$20,655

Government bills end at

$20,624

Best vs worst

$62

The honest reading: over 12 months the spread between your best and worst option is $62, which tells you whether shopping harder is worth an afternoon. Three rules that outlive any rate table. Emergency funds live in easy access, full stop; a locked emergency fund is an oxymoron. Fix only money with a date on it. And in a falling-rate cycle the fixed option is quietly buying insurance against the easy-access rate melting, which is worth more than the headline gap suggests.

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All three end values at your rates, saved.

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Educational information, not financial advice. Figures current as of July 2026 where dated; allowances and rates change, so check the source before acting.