What is the Capital Gains Harvesting / Bed-and-ISA Calculator?
The Capital Gains Harvesting / Bed-and-ISA Calculator helps UK investors understand how much of a taxable investment portfolio could potentially be sold, re-wrapped into an ISA, and managed within Capital Gains Tax allowances.
It is designed for people with investments held outside an ISA who want to explore Bed-and-ISA transactions, annual CGT allowances, and the potential benefits of gradually reducing a taxable portfolio over several tax years.
How the Calculator Works?
The calculator estimates:
- How much of your portfolio could be moved into tax-efficient wrappers
- The indicative CGT impact of planned sales this tax year
- How annual harvesting compares with doing nothing over the longer term
Simply enter your portfolio value, cost basis, planned sales, ISA allowance, and CGT assumptions. The calculator then shows your available capacity, estimated tax position, and a simplified long-term comparison.
Step 1: Enter Your Portfolio Details
Add your current GIA value, original cost basis, realised gains, realised losses, and expected investment growth.
Step 2: Add Tax and Wrapper Assumptions
Enter your CGT assumptions, ISA allowance remaining, planned Bed-and-ISA amount, and any additional sales you expect to make.
Step 3: Review the Results
See how much could potentially be moved into wrappers, your indicative CGT position for the current tax year, and a longer-term comparison of different approaches.
Disclaimer: This calculator provides illustrative estimates only and should not be used for tax filing or financial decisions. UK Capital Gains Tax rules, share matching rules, allowances, and personal circumstances are complex. Always refer to HMRC guidance and seek professional advice where appropriate.
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How investors might use capital gains harvesting in practice
Capital gains harvesting is often most useful when viewed over several tax years rather than as a one-off event. These examples show how different investors might use the calculator to explore their options before 5 April.
Andrew, gradually moving £120,000 into ISAs
Andrew built up a taxable investment portfolio before discovering Stocks & Shares ISAs. He wants to see how many years it could take to gradually move assets into an ISA while managing potential CGT exposure.
- Uses annual £20,000 Bed-and-ISA transactions
- Compares harvesting versus doing nothing
- Reviews potential CGT each tax year
Nina, planning a £50,000 withdrawal
Nina needs money for a house extension and wants to understand how much of the sale could create a taxable gain and whether harvesting beforehand changes the outcome.
- Models a large one-off disposal
- Uses realised losses already available
- Tests different CGT assumptions
David and Claire, planning as a couple
David and Claire want to explore how using two sets of allowances could affect a long-term harvesting strategy, while understanding the limitations of the simplified spouse model.
- Turns on the spouse option
- Tests a 10-year unwinding plan
- Uses the results as a discussion starter with an adviser
What is the Capital Gains Harvesting / Bed-and-ISA Calculator?
The Capital Gains Harvesting / Bed-and-ISA Calculator is an illustrative planning tool for UK investors who hold investments in a General Investment Account. It helps users explore how much they may be able to sell, harvest, and move into tax-efficient wrappers while understanding the potential CGT implications under simplified assumptions.
What is capital gains harvesting?
Capital gains harvesting is the process of deliberately realising gains to make use of available CGT allowances and reliefs, often before the end of a tax year.
What is Bed-and-ISA?
A Bed-and-ISA transaction involves selling investments held in a taxable account and then repurchasing investments inside an ISA wrapper, helping move future growth and income into a tax-efficient environment.
Why do people use Bed-and-ISA strategies?
Many investors use Bed-and-ISA strategies to gradually move taxable investments into ISAs over several tax years while managing potential CGT exposure
How much can I move into an ISA?
The amount depends on your remaining ISA allowance, portfolio value, and other assumptions entered into the calculator.
Does the calculator include same-day and 30-day matching rules?
No. These rules can significantly affect real-world CGT calculations and are not fully modelled within the calculator.
Does the calculator include HMRC share pooling rules?
No. It uses simplified assumptions and does not perform per-holding share pooling calculations.
Can I use my spouse’s CGT allowance?
The calculator includes an illustrative spouse or civil partner option, but it does not model transfers, ownership structures, or tax outcomes in detail.
Does the calculator automatically work out my CGT rate?
No. CGT assumptions are entered by the user. The calculator does not automatically calculate tax bands based on salary, dividends, or other income.
Does the calculator include platform fees or dealing costs?
No. Transaction costs, spreads, fees, and settlement timing are not included.
Is the longer-term comparison a forecast?
No. It is a simplified educational model designed to show how different approaches may diverge over time.
What tax year does the calculator use?
The calculator is designed around the UK tax year running from 6 April to 5 April.
Can I export my results?
Yes. Results can be downloaded as a CSV, with optional email capture depending on site settings.
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Certified Money First Aider®
These calculators are built by a Certified Money First Aider to help you think more clearly about money and time. Money First Aid® is about practical, non-judgemental support for financial wellbeing. The calculators can certainly help you make informed decisions, but they are not regulated financial advice.
