Both are FCA regulated and FSCS protected. The real differences are fees, investment range and how each platform feels to use. Here is the honest comparison.
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.
| 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 plus 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 0.45% applies |
| SIPP | Included in the monthly plan | 0.45% platform fee (0.15% above £100k), no subscription |
| Withdrawals | Free | Free |
| Minimum to start | No minimum (£25/month for regular investing) | £1 |
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 combined £1/month plus 0.45% is repeatedly flagged as expensive for small balances.
Read Moneybox reviews on TrustpilotInteractive 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 price: £1 a month plus 0.45% is one of the higher fee stacks here once your balance grows. It is a great first platform, and many users graduate to cheaper ones later.
A 0.2% fee difference is worth optimising. Knowing whether you are saving enough in the first place is worth far more. Delphina models your pensions, ISAs and investments and tells you where you actually stand.