Every personal finance article tells you to have an emergency fund. Almost none of them tell you the practical bits: how much is enough for you, where to keep it without sacrificing access, and the right order to fill it relative to other money goals. This is the practical version.
The traditional answer is "three to six months of essential outgoings." That's a fine starting point, but the right number depends on a handful of personal factors.
"Essential outgoings" means the bills you genuinely cannot turn off in a hurry: rent or mortgage, council tax, utilities, food, transport, minimum debt repayments, childcare, insurance. Not Netflix, not the gym, not the holidays. For most UK households, essential outgoings are 60–75% of total spend.
Take a household with £3,400/month of total spend, of which £2,200 is essential. A three-month fund is £6,600. A six-month fund is £13,200. A reasonable target for most stable two-income households would be £6,600–£9,000. For a single-income freelancer with two kids, £13,200–£20,000.
The fund needs three things: rapid access, security, and a rate that at least keeps pace with inflation. Here's the ranked list of UK options in 2026.
Top-end easy-access Cash ISAs pay around 4–4.5% AER. Interest is tax-free and the money is instant-access. The annual £20,000 contribution limit is rarely a constraint for emergency-fund purposes. This is the default first home for an emergency fund unless you've already filled your ISA elsewhere.
Sometimes pays a fraction more than a Cash ISA. Useful if you've already used your ISA allowance for the year. The PSA covers up to £1,000 of interest tax-free for basic-rate taxpayers, so for most people the taxable account is functionally identical to an ISA on the first £20–25k of fund.
The dark horse. Average expected return of around 4.0% (the prize fund rate), tax-free for everyone regardless of band. Maximum holding £50,000 per person. The catch: prizes are random, and the average return only materialises with a sizeable balance. Below £10,000 of bonds, your actual return often falls well short of average. Above £30,000, results converge to the prize fund rate. Especially attractive for additional-rate taxpayers who get £0 PSA.
UK money market funds (e.g. those tracking SONIA) pay close to base rate after fees, with daily access. The wrinkle: settlement times mean money takes 2–4 working days to reach your bank. Useful for a "second tier" emergency fund — money you almost never touch — but not the right home for the first £5–10k.
Generally not appropriate for an emergency fund. The whole point is rapid access. The 0.2–0.5% rate uplift you get from a 90-day notice account is rarely worth losing the speed of access in a real emergency.
Most "money order of operations" guides put the emergency fund first. That's roughly right but worth nuancing.
They build the fund and then forget about it. Three years later, the rate that was 4.5% AER on opening is now paying 1.5% because the bank pulled the bonus. Set a calendar reminder to check the rate every six months and switch if there's a better easy-access option. Five minutes of admin can be worth 1–2% extra on a five-figure balance.
Want to see how a £200/month emergency fund habit compounds? See how a regular saving habit grows.
Either works. Jointly gives both parties immediate access in a real emergency. Solely under one name lets the higher-PSA partner shelter more interest tax-free if you're outside an ISA. Most couples split: a shared instant-access account holding the first 1–2 months, plus single-name ISAs for the bulk.
For a small portion, yes — for the cushion above your true essential 3-month figure. The risk is that an emergency hits during a market drawdown and you sell at a loss. Pure-cash for the first tier, mixed for the surplus, is a defensible compromise.
For a basic-rate taxpayer with a £10k fund, a 4.5% Cash ISA produces £450/year guaranteed. Premium Bonds at the prize fund rate average £400/year on £10k but with high variance — many years pay £200, occasional years pay £600. ISA wins for predictability. For higher- and additional-rate payers without ISA allowance left, Premium Bonds win on tax.
Keep it in an account you don't see day-to-day. A separate building society without a debit card. Or in another bank entirely. The two-click friction stops impulse spending; the genuine emergency makes the friction trivial.
This article is general information about UK personal finance. It is not regulated financial advice and Pennywise Finance is not authorised by the Financial Conduct Authority. For decisions involving large sums or complex situations, please consult an FCA-authorised adviser.