All tools Blog About Try the full app →
WealthR  /  Free tools  /  Bed-and-ISA Calculator
✦ Free UK calculator · 2025/26 rules

Bed-and-ISA Calculator UK

Selling a holding from your General Investment Account and rebuying it inside an ISA is one of the highest-leverage tax moves a UK investor can make. This calculator shows you the upfront CGT bill, the long-term tax saving, and the year your future self breaks even — using current 2025/26 UK tax rules.

🛏️
Your Bed-and-ISA situation
All inputs in £ unless marked. Updates as you type.
£
£
£
£
%
%
Amount you can Bed-and-ISA
£20,000
Limited by ISA allowance
CGT bill on disposal
£600
£3,000 of gain after allowance · 20%
Lifetime tax saved (est.)
£8,200
Over 20 years, vs leaving in GIA
Break-even year
Year 2
When tax saving exceeds CGT bill
✅ Yes — Bed-and-ISA looks worth it.
Your CGT bill on disposal is small relative to the long-term tax savings inside an ISA. Over 20 years you'd save roughly £8,200 in tax — a lot more than the £600 cost upfront.
ⓘ Estimates use HMRC 2025/26 rates: CGT 10%/20%, dividend allowance £500, dividend tax 8.75% / 33.75% / 39.35% by band. Calculations assume the GIA equivalent realises gains via periodic rebalancing and the ISA does not. This is a planning aid, not personal tax advice — consult an authorised adviser before acting.
✦ The full picture

What is Bed-and-ISA, and why does it matter?

If you hold investments in a General Investment Account (GIA) — the unwrapped account most UK platforms default you into when you've used up your ISA — every penny of growth, every dividend, and every disposal is potentially taxable. Inside a Stocks and Shares ISA, none of it is. Bed-and-ISA is the legal, HMRC-recognised process of selling a GIA holding and rebuying it inside your ISA on the same day, locking those holdings into the tax-free wrapper for the rest of their life.

The "bed" comes from the older "bed and breakfast" tactic — selling a holding before the tax year ends and rebuying it shortly after to refresh your cost basis. HMRC closed that loophole in 1998 with the 30-day rule. Bed-and-ISA still works because the rebuy happens inside a different legal wrapper — your ISA is treated as a separate beneficial owner for tax purposes. Same security, same broker, same day — completely legitimate.

What you actually save

Three things stop being taxable the moment your holding is inside an ISA:

The longer the holding stays inside the ISA, the more it compounds free of HMRC drag. For a £20,000 holding throwing off a 2% dividend yield to a higher-rate taxpayer, that's roughly £400 of dividend income each year — about £135 of avoided tax annually, before you even count CGT savings on rebalancing.

⚠ The trade-off

Bed-and-ISA crystallises a disposal for CGT purposes. If your gain on the sold portion is bigger than your remaining annual exempt amount (£3,000 for 2025/26), the excess is taxed today at 10% or 20%. The whole question is whether tomorrow's tax savings outweigh today's tax bill — which is exactly what the calculator above answers.

Why investors don't always do it

Three reasons:

Timing — when in the tax year to act

The UK tax year runs 6 April to 5 April. Two practical considerations:

If you're staging across multiple tax years, you can Bed-and-ISA on 5 April and again the next day on 6 April — using two years' worth of CGT allowance and ISA capacity in 24 hours.

Common variations

When it's not worth doing

For most UK investors, none of these apply, and the calculator will quickly show whether the maths supports the move.

✦ How the calculator works

Methodology

1
Calculate the disposal gain
Gain = Holding value − Cost basis. We assume the entire holding has the same average cost basis (your section 104 pool).
2
Apply the CGT annual exempt amount
Taxable gain = Gain − (£3,000 − allowance already used). 2025/26 annual exempt amount is £3,000.
3
Apply your CGT rate
Basic-rate taxpayers pay 10% on shares above the allowance; higher and additional rate pay 20%. (Residential property uses different rates — not modelled here.)
4
Cap by ISA allowance
You can only Bed-and-ISA up to your remaining annual ISA allowance (max £20,000 across all ISAs for 2025/26).
5
Project forward — GIA scenario
Annual dividend tax above the £500 dividend allowance, plus periodic rebalancing CGT. Compounds over the years held.
6
Project forward — ISA scenario
Same growth, zero tax drag. The difference between the two future values is your lifetime tax saving.
7
Find break-even
The first year in which cumulative ISA tax savings exceed the upfront CGT cost — this is your payback horizon.
✦ Common questions

Bed-and-ISA FAQ

What is Bed-and-ISA?
Bed-and-ISA is a process where you sell investments held in a General Investment Account (GIA) and immediately repurchase them inside a Stocks and Shares ISA. This shelters all future growth, dividends, and disposals from UK income tax and capital gains tax. The "sale" counts as a disposal for CGT purposes, so you may owe CGT on any gain above your annual exempt amount (£3,000 for 2025/26).
Do I have to pay CGT when I Bed-and-ISA?
Yes — selling the GIA holding is a disposal, even though you immediately rebuy inside the ISA. If your gain on that disposal exceeds your remaining CGT annual exempt amount (£3,000 for 2025/26), the excess is taxed at 10% (basic rate) or 20% (higher/additional rate) for shares and funds. Many investors stagger Bed-and-ISA across multiple tax years to use the allowance each year and avoid a one-off CGT bill.
Is Bed-and-ISA worth it?
Almost always, yes — provided the CGT bill on disposal is small relative to the future tax savings. Inside an ISA, dividends and capital gains are completely tax-free for life, so even modest holdings tend to save thousands over a 10–20 year horizon. The calculator above gives you the actual numbers for your situation, including a break-even year.
What is the 30-day rule and does it apply?
The 30-day "bed and breakfast" rule says you can't sell shares and rebuy them in your own name within 30 days without HMRC matching the disposal. The Bed-and-ISA exception is that the rebuy is inside an ISA — a different beneficial owner for tax purposes — so the rule does not apply. You can sell in your GIA and rebuy the same security inside your ISA on the same day.
How much can I Bed-and-ISA each tax year?
You're limited by your annual ISA allowance, which is £20,000 for 2025/26 across all your ISAs combined (Stocks & Shares, Cash, Lifetime ISA up to £4,000, Innovative Finance). If you've already paid into an ISA this tax year, only the unused portion is available for Bed-and-ISA. There's no separate Bed-and-ISA cap.
When is the deadline?
The UK tax year runs from 6 April to 5 April. Bed-and-ISA must be completed by 5 April to use that year's ISA allowance — and most platforms have an internal deadline a few working days earlier (typically late March) to allow time for the trade to settle. Allowances do not roll over.
Can I Bed-and-ISA inside a Lifetime ISA or Junior ISA?
You can Bed-and-ISA into a Lifetime ISA, but the LISA cap is £4,000/year (counting toward your £20,000 overall ISA allowance), and you'll need to be aged 18–39 to open one. Junior ISAs belong to the child, so you can't Bed-and-ISA your own holdings into one — but you can gift cash and the child can hold investments inside their JISA.
What about same-day matching?
Same-day matching applies to disposals matched against acquisitions in the same name on the same day. Because Bed-and-ISA moves the asset to a different legal wrapper (the ISA), same-day matching does not apply — your CGT calculation uses your section 104 holding pool average cost basis, not the rebuy price.
Should I Bed-and-ISA losses?
If a holding is at a loss, selling crystallises that loss and you can use it against current-year or carried-forward gains — but only if you formally claim it within four years. Re-buying inside an ISA breaks the chain for future loss matching. For most investors this is fine; for active traders it's worth modelling carefully.
Does WealthR track Bed-and-ISA for me?
Yes. The full WealthR app has a Pro Tax Optimiser that automatically flags Bed-and-ISA candidates from your tracked holdings, factors in your remaining ISA allowance and CGT annual exempt amount for the current tax year, and tracks the actual disposal once you record it.

Want this baked into your full plan?

WealthR's Pro Tax Optimiser flags Bed-and-ISA candidates automatically from your tracked GIA holdings — with your live ISA allowance, CGT used so far, and tax year deadline all accounted for. Free to try, takes about five minutes.

Try the full app → More free calculators
Related
Coast FIRE UK Calculator All free tools UK investing blog WealthR full app