What it means
Every tax system that taxes capital gains has to decide when a gain or loss becomes real, and the natural answer is disposal: nothing counts until the asset is sold. The bed and breakfast deal exposed how mechanical that answer is, because a sale followed immediately by a repurchase is a disposal on paper and barely a change in substance.
The mechanics were simple: an investor holding shares showing a paper loss sold them near the close, often on the last day of the tax year, and bought the same shares back the next morning. The sale created an allowable capital loss that could shelter gains elsewhere, while the repurchase restored the position at roughly the same price, minus dealing costs and one night of market risk.
The United Kingdom's tax authority responded in 1998 with what is now the 30-day rule: if you sell shares and repurchase the same class of shares within 30 days, the sale is matched against the repurchase rather than against your original holding, so the hoped-for loss largely disappears. The official capital gains manual still sets out these matching rules.
The rule killed the overnight version but not the underlying goal, since investors who want the loss must now stay out of the security for a full 30 days, accepting real market risk during the wait, or find another way to keep their exposure while the clock runs. Three workarounds became standard.
With a contract for difference, the investor sells the shares, holds a CFD on the same stock for the waiting period, then repurchases after 30 days, keeping economic exposure without owning the shares; with bed and spouse, the partner buys the shares the seller disposed of; and with bed and ISA, the repurchase happens inside a tax-sheltered individual savings account. Each workaround has its own texture, since CFDs add financing, leverage and counterparty risk and are barred for retail investors in some jurisdictions, including the United States.
Bed and spouse relies on the couple being treated as separate persons for the matching rules, and bed and ISA moves the holding into a wrapper where future gains escape tax altogether. For a manager running money or advising a family, the lesson generalises beyond one British rule.
Tax-loss harvesting only works when the loss survives the system's matching and anti-avoidance rules, and every jurisdiction draws that line somewhere: the United States uses a wash sale rule with a similar 30-day window. The planning question is never just 'can we sell' but 'what must we give up, and for how long, before we may buy back'.
In practice
Real-world examples.
Example
A trader sells a losing holding on the last day of the tax year and buys it back 31 days later to preserve the allowable loss. During the month she stays out of the shares and accepts that the price may rise. The loss is matched to her original cost and shelters gains made earlier in the year.
Example
An investor sells shares at a loss and has her spouse purchase the same shares that afternoon under a bed and spouse arrangement. The household keeps its exposure, while the loss is recorded in the seller's name. The planning relies on the couple being treated as separate persons for the matching rules.
Example
A saver sells a depressed fund in a taxable account and repurchases it inside an ISA, sheltering all future gains. The loss is realised outside the wrapper, and any recovery in the fund's price will be tax-free inside it. The annual limit on ISA subscriptions caps how much can be moved this way.
Formula
Calculation
There is no formula; the constraint is the matching rule: a sale followed by a repurchase of the same class of shares within 30 days is matched to that repurchase, so the allowable loss is sale proceeds minus repurchase cost rather than sale proceeds minus original cost.
Worked example: an investor bought 10,000 shares at $3.50, a cost of $35,000, and sells them at $3.00 for $30,000. If she repurchases the next morning at $3.00 for $30,000, the allowable loss is $30,000 - $30,000 = $0. If she waits 31 days, the sale is matched to her original cost and the allowable loss is $35,000 - $30,000 = $5,000. At an illustrative tax rate of 20% on the gains it shelters, that loss is worth $5,000 x 0.20 = $1,000, which is the figure to weigh against dealing costs, financing charges and the market risk of staying out for a month.Case study
Seen in the real world.
This is a fictional, illustrative example. An investor holds 10,000 shares bought at $3.50, now trading at $3.00, a paper loss of $5,000. She sells, holds a CFD on the shares for the required month, then repurchases, keeping both the allowable loss and most of the market exposure.
The cost of the manoeuvre is not zero. The CFD charges financing and dealing costs, and a sharp move in the share price during the month would produce gains or losses on the CFD that she did not plan for. At an illustrative 20% rate the $5,000 loss is worth $1,000, so she checks that those costs are well below that figure before acting.
Watch out
Common mistakes.
- Repurchasing inside the 30-day window and expecting the loss. The matching rules pair the sale with the new purchase, so the loss is deferred or denied and the exercise earns only dealing costs.
- Treating a CFD as risk-free exposure for the waiting month. A CFD carries leverage, financing costs and counterparty risk, and a sharp move can cost far more than the tax saved.
- Assuming the rule is uniquely British history. The United States wash sale rule and similar regimes elsewhere impose the same 30-day discipline, so the planning logic travels even when the statutes differ.
Questions
People also ask.
What is a bed and breakfast deal?
It is a former UK tactic of selling shares late one day and repurchasing them the next to crystallise a capital loss while keeping the position, a practice ended for tax purposes by the 30-day rule in 1998.
Is bed and breakfasting still possible?
Not in its overnight form: shares repurchased within 30 days are matched to the repurchase, killing the loss. Investors instead wait out the 30 days or keep exposure through CFDs, a spouse's purchase, or an ISA.
What is the bed and ISA strategy?
You sell the investment in your taxable account and repurchase it inside an individual savings account, realising the loss outside the wrapper while all future growth happens tax-sheltered inside it.
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