Bed and ISA Explained: Rules, the 30-Day Rule and the Catch

If you hold investments outside an ISA, you are exposing their future growth and income to capital gains tax and dividend tax. Bed and ISA is the standard way to fix that: you sell the unwrapped holding and buy it straight back inside your ISA, so from then on it grows tax-free. This guide covers the rules, the tax angle, and the catch most people miss.

What is Bed and ISA?

Bed and ISA is a two-step move. You sell an investment held in a general investment account (GIA) or held directly, then immediately buy it back within your stocks and shares ISA, using your annual ISA allowance. The name is a nod to the old "bed and breakfasting" trick of selling and rebuying overnight. Most UK platforms run it as a single instruction so you are out of the market for only a moment.

The point is the wrapper, not the shares. You usually end up holding the same investment - but once it is inside the ISA, all future gains and dividends are sheltered from tax for good.

How the Bed and ISA rules work

There are three rules that matter:

• It uses your ISA allowance. The buy-back counts as a fresh ISA subscription, so the amount you move is limited by how much of your annual allowance is left. You can check what you have left with our ISA allowance calculator.
• The sale is a disposal for capital gains tax. Selling the unwrapped holding is a real disposal, so any gain counts towards your annual capital gains tax allowance for the year (see below).
• You can only move what fits. If your holding is worth more than your remaining ISA allowance, you can move part of it now and the rest in a later tax year.

Bed and ISA and capital gains tax

Because the sale is a genuine disposal, it can trigger capital gains tax if the gain is above your annual exempt amount. The trick is to use that allowance deliberately. If your gain on the holding is within the annual exempt amount, the sale is tax-free and you have moved the investment into the ISA at no CGT cost. Our CGT allowance calculator shows how much of your allowance is still available this year.

Many people Bed and ISA gradually - moving a slice each tax year that keeps the realised gain inside the annual exempt amount - so they shelter the holding over time without ever paying CGT. Doing the sums for your own position, including your exact acquisition cost, is something to confirm with HMRC or an adviser.

Does the 30-day rule stop Bed and ISA?

This is the question that confuses people. The 30-day rule (sometimes called the bed and breakfasting rule) says that if you sell shares and buy the same shares back within 30 days, the sale is matched against the repurchase rather than your original holding - which can cancel out the gain you were trying to realise.

Here is the key point: the 30-day rule does not apply to Bed and ISA. The rule matches a sale to a repurchase of the same shares in the same capacity. When you buy back inside an ISA, that is treated as a different acquisition, so the original disposal stands and your gain is realised as intended. That is exactly why Bed and ISA works where a simple sell-and-rebuy in the same account would not.

Bed and ISA sidesteps the 30-day rule because the buy-back happens inside the ISA wrapper, which counts as a separate acquisition from the unwrapped shares you sold.

Bed and ISA disadvantages

It is not free of downsides. Weigh these up first:

• Dealing costs and spreads. You pay any dealing charges twice (sell and buy) and cross the bid-offer spread, so a tiny holding may not be worth moving.
• A capital gains tax bill if you overshoot. If the realised gain is above your annual exempt amount, you crystallise a CGT charge now rather than later.
• Time out of the market. You are briefly uninvested between the sale and the repurchase, so the price can move against you.
• It uses allowance you might want elsewhere. Every pound you Bed and ISA is a pound of ISA allowance you cannot use for new savings that year.

Is Bed and ISA worth it?

For most long-term investors with holdings outside a wrapper, yes. Sheltering future growth and dividends from tax is one of the highest-value, lowest-effort moves available, and using your annual allowances each year means you can often do it without paying any tax at all. The main exceptions are very small holdings where costs outweigh the benefit, and cases where the gain would push you well over your annual exempt amount in one go.

The practical approach: check your remaining ISA allowance, check your remaining CGT allowance, and move as much as fits inside both - repeating each tax year until everything is wrapped.