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.
Fund investors who value guidance, tools and phone support.
Portfolios above roughly £60k where a flat fee beats percentage charges.
Tick what you need. No account, no email. The answer is on this page.
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.
Reviewers highlight helpful phone support and a straightforward transfer process.
The £7.50 share dealing charge and dated parts of the website draw criticism.
Read Fidelity reviews on TrustpilotLong-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 Trustpilot| Fee | Fidelity | Interactive Investor |
|---|---|---|
| Platform fee | 0.35% from £25k to £250k; 0.20% from £250k to £1m; nothing above £1m; £90 a year flat under £25k without a regular savings plan | Core £5.99/month (up to £100k); Plus £14.99/month (no limit); Premium £39.99/month |
| Share dealing | £7.50 per online trade | £3.99 per trade (£2.99 on Premium) |
| Fund dealing | Free | £3.99 per trade (£2.99 on Premium) |
| FX fee | 0.75% tiered | 1.5% on the first £25k, tiered lower above |
| Stocks & Shares ISA | Platform fee applies | Included in the monthly plan |
| SIPP | Platform fee applies | Included in the monthly plan |
| Withdrawals | Free | Free |
| Minimum to start | £25/month or £1,000 lump sum | No minimum (£25/month for regular investing) |
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 Fidelity or Interactive Investor. Delphina is guidance, not financial advice.
Fidelity is a solid full-service choice for fund investors. Fund dealing is free, the ETF and share service fee is capped at £90 a year, and the guidance content is some of the best of the big platforms.
Costs are less friendly if you trade shares often or hold a small account without a regular savings plan. Compare it against AJ Bell if you want similar breadth with lower dealing charges.
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.
Interactive Investor charges a flat monthly fee whatever you hold: £5.99 a month (£71.88 a year) on Core. Fidelity charges a percentage on funds: 0.35% from £25,000 to £250,000, or a flat £90 a year under £25,000 unless you have a regular savings plan.
With a Fidelity regular savings plan, 0.35% passes £71.88 at around £20,500 in funds. Above that, ii's flat fee costs less in platform fees. Our data shows Core covering portfolios up to £100,000. Above that, the Plus plan is £179.88 a year.
Trading costs differ too. ii charges £3.99 a trade on Core and Plus, Plus includes one free trade a month, and regular investing is free. Fidelity charges nothing to deal in funds and £7.50 per online share trade, or £1.50 through a regular savings plan.
At ii the SIPP is included in the plan price, so having an ISA and a SIPP does not add a second plan fee. At Fidelity the SIPP is charged on the same tiers as the ISA, with the fee on shares, ETFs and investment trusts capped at £90 a year.
You can usually access a personal pension from 55, rising to 57 from 6 April 2028. Neither platform offers a Lifetime ISA. Both offer a Junior ISA.
ii starts the transfer, because transfers are started by the provider you are moving to. Fidelity charges no exit or transfer fees on funds. Holdings move in specie (without being sold) where ii holds the same investment. Anything it does not offer is sold to cash first.
If you are moving the other way, Fidelity starts the transfer. We have not listed ii's exit charges here, so check them before you begin.
If you are weighing this up before the end of the month, add up the value of your ISA and SIPP. That one number tells you which side of the £20,500 crossover you are on.
It depends on what you hold and how often you trade. Fidelity's platform fee is 0.35% from £25k to £250k; 0.20% from £250k to £1m; nothing above £1m; £90 a year flat under £25k without a regular savings plan, against core £5.99/month (up to £100k); Plus £14.99/month (no limit); Premium £39.99/month at Interactive Investor. On dealing, Fidelity charges £7.50 per online trade for shares and free for funds, while Interactive Investor charges £3.99 per trade (£2.99 on Premium) for shares and £3.99 per trade (£2.99 on Premium) for funds. Fees verified July 2026.
Fidelity is best for fund investors who value guidance, tools and phone support. Interactive Investor is best for portfolios above roughly £60k where a flat fee beats percentage charges. Both are FCA regulated and covered by the FSCS.
On Fidelity's ISA: Platform fee applies. On Interactive Investor's ISA: Included in the monthly plan. Neither offers a flexible ISA, so anything you withdraw still counts against your annual allowance. Minimums are £25/month or £1,000 lump sum at Fidelity and No minimum (£25/month for regular investing) at Interactive Investor.
Fidelity offers a SIPP (platform fee applies). Interactive Investor offers a SIPP (included in the monthly plan).
Fidelity scores 4.6 out of 5 on Trustpilot (Excellent) from over 6,500 reviews. Interactive Investor scores 4.6 out of 5 (Excellent) from over 28,000 reviews. The £7.50 share dealing charge and dated parts of the website draw criticism. The 1.5% headline FX fee and occasional platform outages are the recurring complaints.
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. Fidelity charges free on withdrawals and Interactive Investor 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.
Fidelity or Interactive Investor, 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.
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