A fund flows story is normally the least interesting thing in an adviser’s inbox. This one is worth an accountant’s attention for a reason that has nothing to do with markets: a very large number of people have quietly changed what their money is invested in, and the first professional who will see the consequence in writing is the one who prepares their tax return.
That is the whole argument of this piece. Cash is a taxed asset in a way that an unsold equity holding is not. When a client moves a substantial sum from one to the other, they have not just changed their risk position — they have created an annual income tax charge that did not exist before, and they will almost certainly not have thought of it that way. The practice finds out about it roughly a year later, in a box on a return.
What Calastone actually recorded
The underlying data is worth stating precisely rather than by headline. According to Calastone’s Fund Flow Index for August 2026, UK equity funds recorded net outflows of £315m in the month — the fourteenth month of outflows in the last fifteen, taking total withdrawals since June 2025 to £15.16bn. August was far calmer than July, which saw £1.61bn withdrawn.
Where the money went matters more than the fact it left. Bond funds took in £407m in August, a fourth consecutive month of inflows. Money market funds took in £364m, their strongest month since November and more than double the twelve-month average. Between them, bond and money market funds have absorbed £8.7bn since the equity outflows began in June 2025.
Edward Glyn, head of global markets at Calastone, put it this way: “Such prolonged outflows from equity funds are incredibly rare… Investors aren’t panicking, but they are stubbornly refusing to chase equity markets higher.” He also noted that “cash is doing more of the talking”, and that Budget speculation was adding to the caution, with some investors concerned about possible changes to capital gains and pension tax reliefs.
None of that is an accountancy story on its face. It becomes one at the point the money lands in an interest-bearing account.
Why this reaches the accountant before anyone else
Consider the mechanics. A client who holds an accumulating equity fund and does not sell it generates no capital gains tax charge at all in the year, however much the holding grows. The gain is unrealised, and when it is eventually realised the first £3,000 of gains in the year falls within the annual exempt amount. There is dividend income to deal with, but it is typically modest relative to the capital.
Move the same money into a deposit account or a money market fund and the position inverts. Interest is taxable in the year it arises, at the client’s marginal rate, with only the Personal Savings Allowance to shelter it — £1,000 for a basic-rate taxpayer, £500 at higher rate, and nil at additional rate. There is no annual exemption of the CGT kind, and no deferral. The return arrives every year, and so does the tax on it.
The client experiences this as a safer decision. The accountant experiences it as a number that has appeared from nowhere. And because the tax follows a year behind the decision, the conversation that would have been useful happened twelve months before anyone had a reason to have it.
Putting real numbers on it
The following is illustrative — a composite built to show the shape of the problem, not a real client and not a prediction about any particular portfolio.
A client earns a salary of £95,000 and, during 2025, moved £250,000 out of equity funds into a mixture of deposits and a money market fund. Take 3.75% as the return — the Bank of England’s Bank Rate, unchanged since 18 December 2025, which is a fair anchor for a competitive deposit or a money market holding.
- Interest for the year: £250,000 at 3.75% is £9,375.
- The client is a higher-rate taxpayer, so the Personal Savings Allowance is £500. Taxable interest is £8,875, and at 40% that is £3,550 of income tax.
- Adjusted net income is now £104,375. Because that is above £100,000, the personal allowance falls by £1 for every £2 of excess — £4,375 over the threshold reduces the allowance by £2,187.
- That lost allowance is itself taxed at 40%, adding a further £875.
Total tax attributable to the interest: £4,425 on £9,375 of income. An effective rate of 47.2% on money the client moved specifically because it felt like the cautious thing to do.
The second and third bullets are the ones a client never anticipates. The headline rate on savings income is the marginal rate, but a client sitting just below £100,000 of income is in a band where each additional pound of interest costs 60p, and a large cash balance is an efficient way to walk into it without noticing. That is not a market view or an investment opinion. It is arithmetic that only becomes visible when someone prepares the return.
The client made an investment decision. What arrived on the accountant’s desk a year later was a tax decision they did not know they had made.
The signal, and how to spot it
What makes this unusually easy to act on is that the evidence is already in the practice’s files. This is not a question that needs asking; it is a comparison that needs running.
The marker is a year-on-year jump in untaxed interest received, particularly where the client’s employment or trading income has not moved. On the return it looks like a single figure that has doubled or worse. In the underlying paperwork it looks like new deposit accounts, or a fund holding that has changed character from equity to money market. Where a client has an investment portfolio the practice sees, the same shift shows up as a change in the mix rather than a change in the total.
Two adjacent patterns are worth checking at the same time. A client outside self assessment who receives a Simple Assessment letter for the first time is very often a client whose savings interest has crossed a threshold. And a client whose company is accumulating cash on the balance sheet raises a different but related set of questions, which we cover in the cash question. Both belong to the broader category of things the practice can already see, discussed in the signals already sitting in your accounts.
The reason clients gave, and why it complicates things
Glyn’s point about Budget speculation deserves separating out, because it changes what kind of conversation this is. If a client moved to cash because they had reached a considered view about market valuations, that is their decision and there is nothing to flag. If they moved to cash because they were worried about rumoured changes to capital gains tax or pension reliefs, then they have taken a certain, immediate and annually recurring tax cost in order to avoid a possible future one.
That may still be the right call. It is not for an accountant to say, and it is not for this article to say either. But it is a materially different position from the one the client believes they are in, and it is the sort of thing that benefits from being modelled rather than assumed. The Chancellor declined to rule out tax rises ahead of the Budget in comments reported by Money Marketing on 7 September 2026, which is precisely the kind of open-ended signal that keeps money sitting still. We looked at how to handle client questions in that window in the pre-Budget question.
What a joined-up conversation looks like here
This is a clean illustration of a division that runs through most of these situations. The accountant holds facts: the size of the interest, the marginal rate it suffers, the allowance it has eroded, whether the £20,000 ISA allowance for the 2026 to 2027 tax year has been used, and what the same money was doing the year before. All of that can be stated to the client without straying anywhere near a recommendation.
What the accountant does not hold is the modelling — whether that much cash is appropriate for this client over their actual time horizon, how it interacts with their retirement plans, what the alternative shapes look like and what each would cost. Those are regulated questions. The boundary is set out in more detail in who does what, and the mechanics of handing a client over, where that is what the client wants, in anatomy of an introduction.
It is worth remembering how few of these clients have anyone doing the modelling at all. The lang cat’s State of Advice Report 2025 found that just 9% of UK adults had paid for financial advice in the preceding two years, while 91% of those who did take advice found it valuable. A great many of the people who collectively withdrew £15.16bn from equity funds did so without advice, and will pay tax on the result without advice too. More on that in the advice gap.
Two things worth doing this week
Both are list-building exercises using information the practice already holds.
First, run the interest comparison. Pull untaxed interest received for the last two years across the personal tax client base and sort by the increase. The clients at the top of that list have moved money, and most of them will not have connected the decision to the tax. This takes an afternoon and needs no new information from anyone.
Second, cross-check that list against £100,000. Any client on it whose adjusted net income now sits between £100,000 and £125,140 is losing personal allowance at an effective 60% rate on the interest, and is the group where the gap between what the client thinks they did and what they actually did is widest. That is a specific, factual thing to raise, and it is the most valuable five minutes in the whole exercise.
What is still uncertain
Two things, and they pull in opposite directions. The tax treatment described above is settled: the Personal Savings Allowance figures, the personal allowance taper and the rate bands are current law for the 2026 to 2027 tax year, and nothing here depends on a forecast. What is genuinely open is the Budget. Capital gains tax and pension tax relief have both been the subject of speculation, the Chancellor has not ruled out tax rises, and until the Budget is delivered nobody knows which of the rumoured changes are real. Any conversation held now should deal with the rules as they stand rather than with the ones a client has read about.
The second uncertainty is the flows themselves. Fourteen months of outflows in fifteen is a well-established pattern rather than a blip, but August’s £315m was a fifth of July’s figure, and Calastone’s own commentary frames investors as waiting rather than fleeing. Whether the money returns to equities, stays in cash, or moves again after the Budget is not knowable now — which is exactly why the useful work is identifying who has moved, not predicting what happens next.
Common questions
Is a money market fund distribution taxed as interest or as a dividend?
It depends on what the fund holds, not on what it is called. A UK authorised fund holding predominantly interest-bearing assets makes interest distributions, which are taxed as savings income and sit against the Personal Savings Allowance — £1,000 for a basic-rate taxpayer, £500 at higher rate and nil at additional rate. An equity fund makes dividend distributions, taxed under the dividend rules instead. The consolidated tax voucher states which kind of distribution has been paid, and it is worth reading rather than assuming from the fund name. Getting this wrong puts the figure in the wrong box and applies the wrong allowance to it.
Does a client have to file a return just because they now have savings interest?
Not necessarily, and that is precisely what makes it easy to miss. Banks and building societies report interest to HMRC directly, and for someone outside self assessment HMRC will usually collect the tax by adjusting a PAYE code or by issuing a Simple Assessment letter. The client sees a letter or a changed tax code rather than a bill they were expecting. For a client already inside self assessment, the interest simply appears in the return. Either way the practice is the first professional to see the size of the number, which is the point worth acting on.
Is an ISA not simply the answer to this?
The ISA allowance is £20,000 in the 2026 to 2027 tax year, and interest or growth inside an ISA is not taxed. So the allowance is plainly relevant, and noting that a client has not used it is ordinary observation. What it is not is a complete answer. £250,000 does not fit inside a £20,000 allowance, the choice between a cash ISA and a stocks and shares ISA is an investment decision, and the sequencing against pension contributions and a client’s wider position is regulated territory. Flagging the unused allowance is the accountant’s part; deciding what goes in it is not.
Does the same issue arise with money held inside the company?
It arises differently, and the two are worth keeping separate. Interest earned on company deposits is taxable profit and increases the corporation tax charge, but there is no Personal Savings Allowance and no personal allowance taper in play. The distinct problems with company cash are the business property relief, trading status and small profits rate tests, which we set out separately in the cash question. What the two situations share is the shape: money moved somewhere quiet for good reasons, generating a consequence that shows up in the accountant’s work rather than in the client’s thinking.
Where does the accountant’s role stop and the financial planner’s begin?
The accountant holds the evidence and can describe it freely. Saying that a client’s savings interest has risen sharply, that it is taxed at their marginal rate, that it has eroded part of their personal allowance and that the ISA allowance is unused are all statements of fact about the return. None of that is a recommendation. What follows — whether the client should hold that much in cash, over what horizon, and what else the money might do — is regulated advice and belongs with an authorised firm. The boundary is what lets the accountant raise the subject at all.