Monmouthshire Building Society Junior Cash ISA

A Junior Cash ISA is a tax-free savings account for a child under 18. An adult with parental responsibility opens and runs it, anyone can pay in, and the child cannot touch the money until their 18th birthday. Monmouthshire Building Society's version is opened by a parent or guardian aged 18 or over, for a child aged below 18, and the society's own product page carries today's interest rate¹.

The amount that can go in each tax year is £9,000 per child, and the tax year runs from 6 April to 5 April¹. That is a limit on the child, not the account: it covers every Junior ISA the child holds, so a second account elsewhere does not create a second allowance.

Monmouthshire Building Society is a mutual building society, which means it has no shareholders, and membership normally comes from holding a qualifying savings account or mortgage³. Its Junior Cash ISA is one of a small number of children's accounts it offers, alongside a Young Saver Account².

What it is and who it is for

A Junior Cash ISA is the children's version of a cash ISA. It is a savings account, not an investment, so the balance does not rise and fall with markets. What makes it different from an ordinary children's savings account is the tax treatment and the lock: interest is exempt from income tax, and the money stays put until the child is 18¹.

The account is for a child under 18. NS&I, which runs the government-backed version, describes its own Junior ISA as being for children aged under 18 who live in the UK, with children under 18 living outside the UK able to hold one only if they are a dependant of a UK Crown servant⁵. Monmouthshire Building Society's own eligibility wording is narrower on residency: the account opener must be a UK resident, excluding Northern Ireland¹.

The adult who opens it is the Registered Contact. Coventry Building Society, which also offers a Junior Cash ISA, describes the role plainly: an adult who has parental responsibility for the child will need to open the junior cash ISA and manage the account⁶. Monmouthshire Building Society's product page says the same in its own words, requiring parental responsibility and an opener aged 18 or over¹.

It suits a child with a long horizon and an adult who wants the money genuinely out of reach. It does not suit anyone who might need to get at the money before the child's 18th birthday, because the rules do not allow it.

How it works

Money paid in earns interest, and the interest is exempt from income tax¹. Monmouthshire Building Society calculates interest daily and pays it once a year, after 5pm on 31 March¹. The tax year itself runs from 6 April to 5 April¹.

The account is opened at a branch or agency, and the society's ISA range more broadly can be opened online, in a branch or agency, or through its app¹. An agency is how the society serves areas without a branch, working with partners such as estate agents, financial advisers and accountants who offer its products face to face⁸.

Accounts are held in the child's sole name, and the child can take control of the account from the age of 16, though the funds stay locked until 18¹. At 18 the account automatically becomes an adult Cash ISA in the child's name, with no application needed². Coventry Building Society describes the same end point for its own account: when they reach 18, their junior cash ISA will convert to an adult cash ISA, and they will be able to access their savings⁶.

Anyone can pay in, not just the person who opened it. Coventry Building Society states that anyone can pay into a child's junior cash ISA, and Nottingham Building Society says grandparents and family members can normally pay in within the annual allowance⁶.

How the fees and charges work

There is no charge to open or run the account, and no product fee. What a saver needs to watch is not a fee but the terms attached to the money: the minimum that has to go in, the maximum the society will hold, and what happens if the rate moves.

The minimum opening balance on the Monmouthshire Building Society Junior Cash ISA is £10, and the maximum balance is £2,000,000¹. That upper figure is not specific to this account. One of those pages adds a detail worth knowing: the £2,000,000 does not contribute to any personal savings accounts held with the society¹⁰.

On rates, the society's product page carries the current figure, and it states that rates and information for the Junior Cash ISA are correct from 19 December 2025¹. Where the rate goes down, the society says it will give at least 14 days notice on this account¹. Its variable rate accounts carry a longer commitment: at least 30 days notice of a rate reduction¹¹. The two statements come from the society's own pages and do not match, so a saver should treat the notice period as at least 14 days and check the account terms for the current position.

There is one more limit that is not a fee but behaves like one. The society states that you can currently only hold one ISA product with it¹². A child with a Junior Cash ISA there could not also hold one of its adult Cash ISAs, though the child's own age rules would prevent that in any case.

Who can apply and how to apply

The person opening the account must be a parent or guardian aged 18 or over, with parental responsibility for a child under 18, and must be a UK resident excluding Northern Ireland¹. The society's product page for the account also states a minimum age of 16 for the account opener in one place while stating 18 or over elsewhere, so the two statements on the same page do not agree¹.

Applying follows the society's usual pattern for its ISA range: online, in a branch or agency, or through the app⁷. The Junior Cash ISA itself is listed as opened at a branch or agency¹. Identification and proof of address are needed, as they are across the society's savings products³.

Building societies in this market differ in how they take applications, which is useful context if the branch route is inconvenient. Nottingham Building Society's Junior ISA can only be opened and managed in branch, with a £1 opening amount and an appointment booked by phone⁹. Newcastle Building Society asks customers to visit a branch with proof of identity for both adult and child and proof of address¹⁴. Suffolk Building Society takes an application form, in branch with cash or cheque or by post with an opening cheque¹⁵. Newbury Building Society opens and operates its Junior Cash ISA in branch or by post¹⁶. Skipton Building Society allows opening and managing in branch or by post¹⁷. Beverley Building Society asks for a signed application form, identification for the child and two forms of identification for the Registered Contact¹⁸.

Transferring in is possible. The society states that you can move an ISA from another provider into it and keep the tax-free benefits, and that transfers can come from a Cash ISA or a stocks and shares ISA⁷. The Junior Cash ISA page states that you can transfer into it from another Cash ISA¹. Nottingham Building Society's equivalent account allows both partial and full transfers in from another Junior ISA or Child Trust Fund⁹. Moving a Junior ISA does not use up any of the child's annual allowance, and the receiving provider arranges the transfer.

How your money is protected

Monmouthshire Building Society savings accounts, including ISAs, are protected by the Financial Services Compensation Scheme up to £120,000 per person, or £240,000 for joint accounts³. The society states separately that both the Junior Cash ISA and the Young Saver Account are protected by the FSCS up to £120,000 per eligible person². Its ISA page repeats the £120,000 per person figure⁷.

That limit is per eligible person, and it applies across accounts held with the same firm. The same principle applies across brands that share a banking licence, which is why it is worth checking which firm stands behind each account a child holds⁸.

The society is authorised by the Financial Conduct Authority, with firm reference number 206052, and appears on the Bank of England's list of building societies incorporated in the UK²¹. Its FCA status is authorised, effective from 1 December 2001, and its permissions include accepting deposits and entering into regulated mortgage contracts as lender²¹. It also trades under the name MONBS²¹.

Protection covers the failure of the firm, not everything that can go wrong. It does not cover a fall in the interest rate, a change to the terms, or a dispute about how the account has been run. Those are complaints, not compensation claims, and they follow a different route.

Problems, complaints and getting help

The most common friction with a Junior Cash ISA is the lock itself. After the 14 day cancellation period, the account cannot be closed and no money can be taken out until the child turns 18¹. That is the rule, not a discretionary charge, and it applies however the money is needed. The 14 day window at the start is the only point at which the decision can be reversed¹.

If something goes wrong with the account, Monmouthshire Building Society has an internal complaints procedure, and the society states that if you are not satisfied with its final response you can refer the complaint to the Financial Ombudsman Service²³. Its complaints page also sets out how a complaint about another firm is handled: with the customer's permission, the complaint is referred to the other firm, with notification in a final response letter²³. The society's own page gives two different ways of making contact, by phone on 0800 0234567 for the ombudsman referral and by phone on 01633 844 340, or in writing to the Complaints Team at Monmouthshire House, John Frost Square, Newport, NP20 1PX, for the complaint itself²³. The two sets of contact details come from the society's own pages and do not match, so check the complaints page for the current route.

The society also offers help to customers experiencing financial or economic abuse, by phone or in a branch when it is safe to do so²⁵. Where a Power of Attorney is needed to run an account for someone else, the society asks for identification for all attorneys and the donor, a completed signatory form, and the original or a certified copy of the document, and says registration can take up to 5 working days²⁶. It also states that you must not register for its mobile app until the Power of Attorney registration has been completed²⁶.

Free, impartial help is available from MoneyHelper, and the Financial Ombudsman Service handles unresolved complaints about ISA providers. For a child's account, the person who can complain is the Registered Contact, since they are the one who opened and manages it.