Both are FCA-regulated and FSCS-protected. The real difference is fees, account types and how each platform feels to use. Verified against each provider’s published charges.
Fees verified July 2026. Capital at risk. Information, not financial advice.
Portfolios above roughly £60k where a flat fee beats percentage charges.
Beginners building a habit, and first-time buyers using the Lifetime ISA.
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Tick what you need above and we'll tell you which of the two covers it.
Account availability verified July 2026. Capital at risk. Information, not financial advice.
Long-standing customers value the flat fee and the breadth of investments.
The 1.5% headline FX fee and occasional platform outages are the recurring complaints.
Read Interactive Investor reviews on TrustpilotUsers love the round-ups, the goal-based design and how painless it makes starting. 93% of customers surveyed in 2026 would recommend it.
The £1 monthly subscription on top of the platform fee is often flagged as expensive for balances under £5,000.
Read Moneybox reviews on Trustpilot| Fee | Interactive Investor | Moneybox |
|---|---|---|
| Platform fee | Core £5.99/month (up to £100k); Plus £14.99/month (no limit); Premium £39.99/month | £1/month subscription (waived at £5,000+) plus 0.15% to 0.45% platform fee |
| Share dealing | £3.99 per trade (£2.99 on Premium) | US stocks available, 0.45% FX fee |
| Fund dealing | £3.99 per trade (£2.99 on Premium) | Free (fund fees apply) |
| FX fee | 1.5% on the first £25k, tiered lower above | 0.45% on US stocks |
| Stocks & Shares ISA | Included in the monthly plan | Subscription plus 0.15% on Moneybox funds or 0.45% on other funds |
| SIPP | Included in the monthly plan | 0.45% on the first £100k then 0.15% (other funds); 0.15% capped at £150 a year (Moneybox funds); no subscription |
| Withdrawals | Free | Free |
| Minimum to start | No minimum (£25/month for regular investing) | £1 |
A 0.25% yearly fee gap sounds small. On £50,000 over 20 years it is about £5,900 (illustrative). Add your ISA and pension balances to Delphina yourself and see what your charges cost by retirement and whether you're on track.
See what my fees costIllustrative: £50,000, 5% a year growth before charges, 0.25% vs 0.50% a year in charges, no further contributions. Not a recommendation of Interactive Investor or Moneybox. Delphina is guidance, not financial advice.
Interactive Investor charges a flat monthly subscription instead of a percentage. On a £200,000 portfolio, £5.99 a month is a fraction of what percentage-fee platforms charge, which is why ii keeps winning larger DIY investors.
The equation flips for small pots: £71.88 a year on £10,000 is 0.7%, more than almost any rival. Work out your portfolio size first, then decide.
Moneybox is designed for getting started. Round-ups, weekly deposits and simple starter portfolios remove the friction that stops most people investing, and its Lifetime ISA is one of the most popular routes to a first home deposit.
The convenience has a cost on small balances: £1 a month plus up to 0.45% is one of the higher fee stacks here below £5,000 in non-Moneybox funds. The subscription drops away at £5,000, and Moneybox's own funds carry 0.15% rather than 0.45%, so the total depends on your pot size and fund choice.
It depends on what you hold and how often you trade. Interactive Investor's platform fee is core £5.99/month (up to £100k); Plus £14.99/month (no limit); Premium £39.99/month, against £1/month subscription (waived at £5,000+) plus 0.15% to 0.45% platform fee at Moneybox. On dealing, Interactive Investor charges £3.99 per trade (£2.99 on Premium) for shares and £3.99 per trade (£2.99 on Premium) for funds, while Moneybox charges US stocks available, 0.45% FX fee for shares and free (fund fees apply) for funds. Fees verified July 2026.
Interactive Investor is best for portfolios above roughly £60k where a flat fee beats percentage charges. Moneybox is best for beginners building a habit, and first-time buyers using the Lifetime ISA. Both are FCA regulated and covered by the FSCS.
On Interactive Investor's ISA: Included in the monthly plan. On Moneybox's ISA: Subscription plus 0.15% on Moneybox funds or 0.45% on other funds. Neither offers a flexible ISA, so anything you withdraw still counts against your annual allowance. Minimums are No minimum (£25/month for regular investing) at Interactive Investor and £1 at Moneybox.
Interactive Investor offers a SIPP (included in the monthly plan). Moneybox does not offer a SIPP.
Interactive Investor scores 4.6 out of 5 on Trustpilot (Excellent) from over 28,000 reviews. Moneybox scores 4.4 out of 5 (Excellent) from around 4,800 reviews. The 1.5% headline FX fee and occasional platform outages are the recurring complaints. The £1 monthly subscription on top of the platform fee is often flagged as expensive for balances under £5,000.
Yes. UK platforms accept ISA and SIPP transfers in, and you start the transfer with the receiving provider rather than the one you are leaving. Interactive Investor charges free on withdrawals and Moneybox charges free. Transfer as cash and you are out of the market while it settles; transfer in specie and you keep your holdings but it takes longer.
Interactive Investor or Moneybox, the account is the easy part. What decides when you can retire is how much goes in and for how long. Delphina works that out from what you already hold and what you pay in each month.
Free to check. No card required. Takes about two minutes.