If you’ve got £50,000 or so sitting in savings accounts, you already know something should probably be done with it. That nagging feeling is right — and “invest the lot tomorrow” isn’t the answer.
Give every pound one of three jobs: spending, safety, or growth. Then put each pound where its job gets done. £50,000 in savings accounts means all fifty thousand pounds are doing the same job — and for most of them it’s the wrong one.
Job one and two: spending and safety
Money you’ll spend in the next year or so — a car, a kitchen, a wedding — stays in cash. So does your safety net: three to six months of essential outgoings, sitting somewhere you can reach it in days.
For most households that’s £10,000 to £15,000 all in. Put it in the best easy-access account you can find — the market leaders pay high-threes at the moment — and stop thinking about it. This money’s job is to be there when things go wrong, and it does that job perfectly. Nobody should talk you out of an emergency fund, including me.
What keeping the rest in cash actually costs
Right now, cash looks respectable. Inflation is 2.9%, the best accounts pay a little more, so your savings are just about holding their ground — this year, anyway.
But the growth money — the £35,000 or £40,000 you won’t touch for a decade or more — is playing a twenty-year game. Take £40,000. In a savings account averaging 3.5%, it becomes about £80,000. In a fund tracking the S&P 500, which has averaged around 10% a year over the long run, the same £40,000 becomes about £269,000.
Leaving your growth money in a savings account for twenty years costs you roughly £190,000. Not through any disaster — just quietly, one modest interest payment at a time.
At a cautious 7% a year it still grows to around £155,000 — £75,000 more than cash. And savings rates are more likely to fall than rise from here, while your account’s headline rate quietly drifts down with the base rate.
Where the growth money lives
A stocks and shares ISA — the tax-free wrapper, not an investment in itself — and inside it, a boring index fund as the first thing to buy. You can put £20,000 into an ISA each tax year, so moving £40,000 takes this year’s allowance and next April’s. The rest can wait in cash or a general investment account for its turn.
The government, unusually, agrees. From April 2027 the Cash ISA allowance for under-65s drops to £12,000 — a deliberate shove out of cash and into investing. I rarely side with a Chancellor. On this one I do.
But what if it crashes the day after you invest?
It might. Markets fall roughly once a decade, hard, and nobody can tell you when — the people who claim they can are selling something.
The worst case on record: the unluckiest buyer in modern history put money in at the October 2007 peak, watched it fall 57%, and today has nearly five times his money. You can lose money in a stocks and shares ISA — but here’s what it takes to lose all of it.
And if investing £40,000 in one go feels like more bravery than you own, drip it in — £3,000 or £4,000 a month over a year. The maths says the lump sum usually wins. A drip gets you there too, and you’ll actually do it.
Safety is a job for some of your money. Right now it’s employing all of it.
This is what I write about every week — managing your own money without paying someone 1–2% a year to do it worse. The letter is free.
I am not a financial adviser. Nothing here is personal financial advice. This is my own experience and opinion, shared for information and education. Investing involves risk — the value of investments can fall as well as rise, and you may get back less than you put in. Please do your own research before acting.