Children's inheritance planning: ISAs vs Premium Bonds, short answer.
For short-term access and prize-based savings, Premium Bonds usually suit best. For long-term tax-free growth locked until adulthood, a Junior ISA often works better.
Decision guide: JISA or premium bonds?
Decide by matching the time horizon, access needs, and estate size. Short goals with likely early withdrawals favour Premium Bonds or a cash JISA. Long goals with estate clarity favour a Junior ISA, especially Stocks & Shares for growth.
Keep a clear record of each gift date.
A simple rule: if the goal is under five years, use Premium Bonds or a cash JISA for capital safety. If the goal is five years or more, use a Stocks & Shares JISA to beat inflation.
Record gifts and nominations to manage Inheritance Tax exposure. Gifts by adults can be Potentially Exempt Transfers and become exempt only if the donor survives seven years.
Key takeaways
The adult ISA limit is £20,000 for 2024/25. The Junior ISA annual limit is £9,000 for 2024/25. The IHT nil-rate band is £325,000 for 2024/25.
JISAs lock funds until the child turns 18 and the funds usually form part of the child's estate. Premium Bonds are redeemable at any time and prizes are tax-free but variable.
Splitting savings between a JISA and Premium Bonds can balance growth, access and inheritance clarity. Document gifts and set nominations so executors can find assets later.
How Junior ISAs and Premium Bonds work
A Junior ISA is a tax-free account that the child owns but cannot access until age 18. Premium Bonds are NS&I securities entered into a monthly prize draw and are redeemable on demand.
Both products are tax-advantaged. ISAs are exempt from Income Tax and Capital Gains Tax under HMRC rules. NS&I prizes are tax-free under NS&I terms.
For official guidance see HMRC on ISAs and NS&I on Premium Bonds.
Ownership and control
A JISA opened for a child becomes the child's legal asset. The account manager controls the account until the child can act.
Premium Bonds bought in the child's name are legally the child's assets, held by NS&I. NS&I allows an optional nomination to name who receives proceeds if the child dies before withdrawal.
A bare trust makes the child the absolute owner at 18 and the asset then forms part of their estate. A discretionary trust keeps control with trustees but brings extra tax reporting and charges.
Tax, rules and limits
ISA rules set the annual allowance and tax treatment; check Finance Act updates each year. The main adult ISA allowance is £20,000 and the Junior ISA allowance is £9,000 for 2024/25.
Premium Bond prizes are tax-free and do not count as income for Income Tax. NS&I publishes prize fund rates but those do not equal guaranteed yields.
Inheritance tax and ownership risks
Assets owned by the child usually form part of their estate for Inheritance Tax. Gifts by adults are often Potentially Exempt Transfers and follow the seven-year rule under the Inheritance Tax Act 1984.
A PET becomes fully exempt only if the donor survives seven years from the gift date. If the donor dies within seven years, the gift may be taxed and taper relief may apply.
Executors need clear records to value estates. Undocumented gifts create delays and can trigger HMRC enquiries.
When gifts affect IHT
Small regular gifts within allowance rules normally do not create PETs. Large lump sums into a JISA or Premium Bonds create a clear PET start date the day the gift is made.
If a grandparent gives £50,000 into a child’s JISA and dies five years later, that gift may still count toward their estate for IHT. This point is often missed in casual gifting.
Trust options and nominations
A bare trust makes the child the absolute owner at 18 and the asset then forms part of the child's estate. A discretionary trust keeps assets out of the child's estate but adds complexity and periodic charges.
A nomination with NS&I speeds up the process of deciding who receives Premium Bonds if the child dies. A will nomination helps executors find JISAs and improves clarity when assets pass on death.
Remember the seven-year rule: a gift becomes fully exempt from Inheritance Tax only if the donor survives seven years from the gift date (Inheritance Tax Act 1984).
Gift dating and records matter for household estate planning. Keep bank transfers and a short deed of gift for larger sums.
In practice, a gift into a child’s Junior ISA or buying NS&I Premium Bonds in the child’s name is normally a PET from the donor. The gift falls outside the donor’s estate for IHT only if the donor survives seven years.
If death occurs within seven years, the gift may be chargeable and taper relief can reduce the tax for gifts made more than three years before death. For example, a grandparent gifting £50,000 who dies four years later may face IHT on that sum.
Discretionary trusts keep assets out of the child’s estate but bring periodic IHT charges and reporting.
Clear dating of the gift and keeping bank transfer records are vital. A brief deed of gift also helps within household estate planning.
Returns, odds and expected outcomes
ISAs give predictable average returns depending on the asset mix. Premium Bonds give a probabilistic expected return that depends on prize odds and balance size.
Model choices using expected-value math, not headline rates. Compare median outcomes and percentiles rather than only means.
Use MoneyHelper or Which? Historical data for robust baselines. State your assumptions and test sensitivity to inflation and fees.
Modelling premium bonds
To estimate expected return, multiply the prize probability per bond by prize size and sum across prize tiers. Small and medium balances show high variance and a real chance of no prize for several years.
Example assumption: if odds per £1 bond are 24,000 to 1, a £1,000 holding has about a 1 in 24 chance per year of any prize. That gives a wide spread of possible outcomes and a low chance of steady returns.
Monte Carlo simulations show distribution across percentiles and help choose allocations. Visualise median, 10th and 90th percentiles to see downside risk.
Comparing ISA returns
A cash JISA gives low steady nominal interest. A Stocks & Shares JISA aims for higher long-term returns with volatility.
Over 10–18 years equities have historically outperformed cash after inflation, though past performance is no guarantee. Compare mean return, standard deviation and fees when planning.
For rough planning use 4–6% real return for mixed equity over 10+ years and 0.5–1% for cash, then model outcomes. These assumptions help set expectations for parents and grandparents.
Readers need clear numeric modelling for Premium Bonds to compare like-for-like with ISAs. Using a conservative expected-value of 1.5% per year, a £100 holding gives an expected return of about £1.50 a year.
That means £1,000 gives about £15 a year and £10,000 gives about £150 a year in expected value. These are means, not guarantees, and variance is high.
Over ten years the expected cumulative return on £1,000 would be roughly £150. Many savers will see lower totals in lower percentiles, and some will win larger one-off prizes.
For planning, compare these expected-value figures with a cash Junior ISA at 1% (about £10 a year on £1,000). Then compare with a Stocks & Shares JISA at 4–6% long-term.
Practical steps for grandparents and third parties
Third parties can buy Premium Bonds for a child or gift money into a JISA but must follow ID and nomination rules. Document the gift and keep records that show date and donor identity for IHT.
NS&I accepts online and postal applications for Premium Bonds in a child’s name and allows a nomination. JISAs can be opened by a parent or legal guardian; other adults can pay into an existing JISA within the annual limit.
Keep proof of transfer, confirmation emails and nomination paperwork so executors can locate assets after a donor dies. A simple deed of gift for larger sums reduces later disputes.
How to buy or gift
To buy Premium Bonds for a child use NS&I online or post forms and include the child’s full details. To contribute to a JISA, use the chosen provider’s application and confirm the child has not exceeded the annual limit.
Grandparents should name themselves as donor in a short note and keep bank statements showing the transfer date. That creates a clear PET start date for IHT.
ID, recordkeeping and nominations
Keep a folder with account confirmations, nominations and a short note stating donor, amount and purpose. This helps executors and avoids HMRC delays.
Nominate a beneficiary on NS&I and include accounts in the donor’s will or a list for executors to find. If estate size is uncertain, consult an Independent Financial Adviser authorised by the FCA.
A practical checklist reduces friction and improves recordkeeping. Step 1: confirm whether a Junior ISA already exists and who can open it.
Step 2: if no JISA exists, ask a parent or guardian to open one so you can contribute. Step 3: to buy NS&I Premium Bonds in a child’s name, use NS&I online or postal application and set a nomination.
Step 4: when transferring money, keep a stamped bank transfer or receipt and a short written note stating donor, amount and date. This documents the PET start date for IHT.
Step 5: record nominations and include account details in wills or an executors’ folder so assets are discoverable. Step 6: if the estate might approach the nil-rate band, consider trusts or professional advice.
Mixed strategies and case studies
A mixed strategy splits funds between a JISA for growth and Premium Bonds for liquidity. This balance helps inheritance clarity, access and expected returns.
Case study 1 (5 years): a parent puts £5,000 into Premium Bonds and £5,000 into a cash JISA. The expected median outcome is near capital on both and Bonds give quick access.
Case study 2 (10 years): £10,000 split 60% Stocks & Shares JISA and 40% Premium Bonds. Median models show equity growth beating Bonds on average, but Bonds reduce shortfall risk at withdrawal.
A common case: grandparents gift £10,000 into Premium Bonds for a child for ten years. That gift is a PET and counts toward the grandparent’s estate if they die within seven years. Document the gift date to record the PET start.
Splitting funds between a Junior ISA and Premium Bonds works well when the family wants both growth and access. It matters most when donors document gifts and consider IHT.
For smaller estates this hybrid approach gives useful flexibility. Larger estates should check trust options to manage future tax charges.
5-, 10- and 18-year models
This section provides three model portfolios: Conservative, Balanced and Growth. Simulate median and 10th/90th percentiles under standard assumptions.
Assumptions example: Stocks & Shares mean 5% nominal return, cash 1% nominal, Bonds expected value 1.5% probabilistic. Adjust for fees and inflation in sensitivity notes.
Sample rule-of-thumb splits
University at 18: 60–80% JISA and 20–40% Premium Bonds. First home deposit (15 years): 50/50 then shift to JISA in the last 2–3 years.
Pure inheritance planning: consider trusts and a professional IFA. Trusts change tax treatment and need legal steps.
This comparison is less relevant when estate planning requires trusts or professional estate strategies, when a child already holds trust assets, or if sums are too small for IHT to matter. In those cases seek tailored legal or financial advice.
Action plan and decision checklist
Decide the beneficiary goal and set the timeframe. Document donors and open the chosen accounts.
Step 1: Define goal and horizon. Step 2: Choose the split between JISA and Premium Bonds. Step 3: Open accounts, set nominations and record gifts.
Step 4: Review allocations annually and adjust as the goal nears. If estate value approaches the nil-rate band, seek MoneyHelper guidance and consider an IFA.
See MoneyHelper for planning tools.
Decision matrix
| Goal horizon |
Priority |
Recommended split |
| Under 5 years |
Access, capital safety |
70–100% Premium Bonds or cash JISA |
| 5–10 years |
Balance growth and access |
40–60% JISA, 40–60% Bonds |
| 10+ years |
Long-term growth |
70–100% Stocks & Shares JISA |
Document each gift with donor name, amount, date and intended purpose. That date is the PET start for Inheritance Tax purposes and helps executors value the estate.
Frequently asked questions
Short answers first, then short explanation.
Can premium bonds avoid inheritance tax?
Ownership matters; child-held assets can form part of their estate. Buying Bonds in a child’s name does not remove IHT risk for donors.
Gifts by adults are PETs and become fully exempt only after seven years. Document gift dates to show the PET start.
Can grandparents open a JISA?
Grandparents cannot open a Junior ISA unless they are the child's parent or legal guardian, but they can pay into an existing JISA. Providers differ, so check terms.
If no JISA exists, a parent or guardian must open it. Grandparents can then contribute within the annual limit.
What happens at 18?
The child becomes account holder and can withdraw JISA funds. Premium Bonds remain redeemable at any time if still held by the child.
At 18 a JISA converts to a standard adult ISA and the child controls access. Trusts remain according to their terms until trustees release funds.
When should I get professional advice?
Seek an IFA if the estate is near the nil-rate band or family arrangements are complex. Use FCA-authorised advisers and check the register.
Large gifts, blended family situations or existing trust structures require a tailored plan and may need legal as well as tax advice.
What to do next
Decide the goal, pick a timeframe and choose a split between JISA and Premium Bonds. Document gifts and set nominations, then open accounts with a provider.
If estate value approaches the nil-rate band, consider advice from an Independent Financial Adviser with FCA authorisation and a solicitor experienced in trusts. Review allocations annually and update nominations and wills so executors can find assets.
HTML infographic and simple visualisation below summarises a split strategy by horizon.
Conservative (5 yrs)
Balanced (10 yrs)
Growth (18 yrs)
ISA or premium bond: which?
Match choice to horizon and access. Use an ISA for long-term tax-free growth and Premium Bonds for accessible prize-based savings.
