At first glance, it has a certain appeal. The gain is realised, the base cost is refreshed, and after a month the investor is back where they started. Neat, tidy, job done. Except, in practice, it is often more trouble than it is worth, and sometimes it does not achieve what people think it does at all. HMRC’s share identification rules are designed to stop straightforward “bed and breakfasting” of this kind. If you sell shares or units and then buy back the same holding within the following 30 days, the disposal is normally matched with that later acquisition, rather than simply being washed through your historic pooled cost. That is the trap.
This matters because many clients do not really want to change their investment. They want the tax result without changing the portfolio. In plain English, they are not saying, “I think this fund no longer suits me.” They are saying, “I would like to crystallise a gain, keep the same exposure, and avoid or reduce tax.” The problem is that the rules have anticipated precisely that sort of manoeuvre. So if the same asset is bought back too quickly, the hoped-for reset often does not work in the simple way imagined.
Even where the investor waits long enough to avoid the 30-day matching rule, the exercise can still be underwhelming. If they sell, sit in cash, and only repurchase on day 31 or later, then yes, the disposal can stand on its own for CGT purposes. But what have they actually achieved? They have been out of the market for a month, taken the risk that prices move against them, and may well have paid dealing costs on the way out and on the way back in. Meanwhile, the annual CGT exempt amount for individuals is now only £3,000 for the 2025 to 2026 tax year, which means there is less shelter available than there once was. This is a long way from a magic trick.
That is why, for many clients, the whole exercise is not so much tax planning as tax-flavoured market timing. If markets rise during those 30 days, the investor may end up paying more to get back into the same position. If markets fall, they may feel pleased with themselves, but that is really an investment outcome rather than proof of an elegant tax strategy. Either way, the tax saving is often less impressive than the sales pitch that led to the idea in the first place.
None of this means realising gains is always a bad idea. Far from it. There are perfectly sensible reasons to crystallise gains. Someone may want to use their annual exempt amount rather than waste it. Someone may want to reset the base cost of an asset gradually over time. Someone may want to reduce a future CGT problem while they are still within a lower tax band. Those can all be legitimate planning objectives. But there is a difference between sensible gain realisation and pretending that moving into cash for 30 days somehow outsmarts the legislation.
The more useful question is usually this: what is the client actually trying to achieve? If the answer is “I want future growth and income to sit in a more tax-efficient wrapper,” then a Bed & ISA approach is often far more sensible. That involves selling investments held outside an ISA and repurchasing them within an ISA, subject of course to the annual ISA subscription limit and the practicalities of execution. The key advantage is that future income and gains inside the ISA are sheltered from UK tax. That is a clearer and often more worthwhile objective than temporarily stepping out of the market just to re-enter at the first opportunity.
Another practical alternative can arise where a client is married or in a civil partnership. Transfers between spouses or civil partners are generally made on a no-gain/no-loss basis, which can allow better use of both people’s CGT annual exempt amounts and, in some cases, lower tax bands. That does not make tax disappear, and it must be done properly rather than casually, but it is often a more coherent planning tool than the old “sell, wait, rebuy” idea.
There is also the possibility that the client genuinely wants to change the portfolio. If that is the case, then the conversation should be about suitability, diversification, cost, risk and long-term objectives, not about trying to dress a technical disposal up as something more exciting than it is. Tax should inform good planning; it should not drive pointless choreography. A transaction that exists only to produce a tax result, while leaving the investor economically almost where they started, deserves a hard look before anyone calls it clever.
The truth is that most worthwhile tax planning is less dramatic than people hope. It is about wrappers, allowances, timing, family planning where appropriate, and making sure the portfolio structure matches the client’s wider financial position. It is not usually about trying to sidestep a rule that HMRC wrote precisely to stop people doing the obvious thing.
So, is selling a fund, waiting 30 days and buying it back ever possible? Yes. Is it usually the clever CGT solution people imagine? Not really. For many clients, it is a lot of effort for a result that is either blocked by the rules, diluted by time out of the market, or simply less useful than more straightforward alternatives. The better route is normally to decide what the real planning goal is first, and then use the right tool for that job. That may be an ISA, a phased disposal programme, a spouse transfer, or simply accepting that not every apparent tax wheeze is worth the admin.
This article is for general information only and does not constitute personal financial advice or a recommendation to take any specific action. Tax treatment depends on individual circumstances and may change in future.
