A joint account can help pay bills. It gives no right to manage, move, or open another adult’s ISA. ISAs cannot be joint. Ownership and the tax-free allowance stay with one adult.
You cannot use another adult’s ISA or Premium Bonds as your own. The adult decides unless a provider accepts legal authority. Premium Bonds are limited to £50,000 per person.
Confirm who can give instructions
Check the adult’s capacity and ownership before touching any money.
Ask what help they actually want
Write down what the adult wants you to do. This may mean helping on a phone call, paying a bill, or checking a savings rate.
Ask the adult to explain the choice in their own words. A clear answer shows they can make that decision now.
The typical mistake is treating help with paperwork as permission to move money. It is not permission.
Separate support from authority
Treat each savings product as its own locked cupboard. A joint bank account may give access only to that account. An ISA has one named owner.
ISAs cannot be joint. Payments use that holder’s yearly allowance. The tax-free status belongs to that holder alone.
A bank’s third-party mandate usually covers selected accounts only. It does not automatically allow an ISA transfer, investment switch, or instruction to NS&I.
Use this test before each action: Can the account holder make this decision now? If yes, let them instruct the provider. They can also give authority that the provider accepts. If no, stop and check for an LPA or deputyship.
Where the adult has mental capacity, start with the provider’s authority rules. Do this before assuming one document works everywhere.
A third-party bank mandate can help with a named savings account. It gives only the powers written on that mandate. The account holder can cancel it.
Providers often ask for identification, account details, and signed forms. Each brand may need its own registration process.
In England and Wales, the Office of the Public Guardian can check a registered property and financial affairs LPA. The provider may still need to check the financial attorney.
⚠️ A joint bank account does not give you access to an ISA or Premium Bonds.
Knowing who can instruct the provider prevents the most serious mistake. Next, choose the authority that matches the adult’s situation.
Use the authority that fits the adult
Match the legal route to the adult’s capacity and the job you need to do.
Use a mandate for limited help
Use the provider’s mandate when the adult has capacity and needs limited help. It can suit one named account and a clear task.
Ask the provider what the mandate allows before signing it. Do not assume it covers withdrawals, transfers, or changed bank details.
A mandate is the quick route for limited support. It is not a lasting substitute for legal authority.
Register an LPA before it is urgent
Check for a property and financial affairs LPA. Do not rely on a health and welfare LPA for savings.
This document can cover bank accounts, ISAs, and Premium Bonds. A health and welfare LPA does not manage savings.
If no LPA exists and the adult lacks capacity, apply for a deputyship from the Court of Protection. This can take many months. It is not a same-day solution.
Choose the authority before moving money
Holder has capacity
Support them on calls or use the provider’s mandate.
Best for a single account.
Holder has capacity, needs lasting help
Make and register a property and financial affairs LPA.
Best for future planning.
Holder lacks capacity, no LPA
Seek Court of Protection deputyship.
Do not improvise access.
An attorney or deputy must keep the adult’s savings separate from their own. They must make choices for the adult’s benefit.
Family convenience or future inheritance must not drive the decision. This matters when relatives disagree or the attorney could gain personally.
Record the balance before acting. Record the options you considered. Record why the chosen action meets the adult’s needs. Record where the money went.
Small customary gifts may be possible in limited cases. Substantial gifts, loans, or transfers to yourself need great care. They may need legal authority.
Clear records are a core part of financial safeguarding.
⚠️ Never mix the adult’s money with your own, even for a short time.
The right authority lets you speak to the provider lawfully. The next stage protects the adult’s tax position and savings record.
Protect ISAs and premium bonds
Keep the adult’s money, tax position, and records separate at every stage.
Handle an ISA without losing its shelter
Ask the ISA provider if it accepts instructions from an attorney or deputy. Ask before opening, paying in, withdrawing, or transferring an account.
Send the authority document, your ID, and the holder’s details by the provider’s stated route. The registration check can take time.
Use the provider’s ISA transfer process when moving an ISA. Do not withdraw money into your own account and repay it elsewhere.
That shortcut can break the transfer trail. It can also affect the ISA’s tax shelter.
Treat premium bonds as a separate holding
Premium Bonds remain the adult’s holding, even when you hold authority. The £50,000 limit applies to the registered holder.
| Action | ISA | Premium Bonds | Check first |
|---|
| Add money | Uses holder’s allowance | Cannot exceed £50,000 | Authority and source of funds |
| Change bank details | Provider security review | NS&I security review | Attorney registration |
| Move savings | Use formal ISA transfer | Cash out or reinvest under NS&I rules | Written provider process |
⚠️ Keep a dated log of calls, transfers, and reasons for each decision. This protects the adult. It also shows that money was used only for their benefit.
Do not overlook savings accounts outside an ISA. Easy-access accounts, notice accounts, and fixed-term bonds remain the adult’s property.
These accounts can have different withdrawal, notice, and maturity rules. Ask the provider what it accepts from an attorney, deputy, or authorised third party.
A fixed-term account may roll into another account at maturity unless the provider receives instructions.
Compare the new rate, access needs, and deposit-protection position in the adult’s name. Then keep the confirmation.
Moving money because it is easier for the helper is not enough. The decision must reflect the adult’s needs and risk tolerance.
⚠️ Do not move ISA money through your own account, even if you plan to return it immediately.
This guide does not apply if the saver is under 18 or has died. Executors deal with the estate after a death. It also does not apply where a capable adult only wants advice and will manage their own accounts. Seek legal advice if there is family conflict, suspected financial abuse, or doubt about mental capacity.
Questions & answers
Can a joint holder manage an ISA?
No. A joint holder needs authority that the ISA provider accepts. ISAs cannot be joint, and the allowance belongs only to the named holder.
Can an attorney open an ISA?
A property and financial affairs attorney may open one if the provider accepts the registered LPA. They must act in the donor’s best interests. They must follow any LPA restriction.
Can I buy premium bonds for an adult?
Do not assume you can buy them as a gift. Confirm NS&I’s current holder, payment, and authority process. The £50,000 limit applies to the registered holder.
Does an LPA cover every provider?
A registered LPA gives legal authority, but each provider may need separate identity checks and registration. Allow 1 to 3 weeks for routine checks. Some checks take longer.
The essentials:- Capacity comes first: a capable adult keeps control of their own savings.
- A joint bank account does not create rights over an ISA or Premium Bonds.
- A provider mandate is limited, while a property and financial affairs LPA must be registered before use.
- Use each provider’s process and keep clear records showing that the money belongs to the adult.
