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.
Hands-off investors happy to hold only Vanguard index funds and LifeStrategy.
Portfolios above roughly £60k where a flat fee beats percentage charges.
| Fee | Vanguard | Interactive Investor |
|---|---|---|
| Platform fee | £4/month minimum below £32k; 0.15% above £32k, capped at £375/year | Core £5.99/month (up to £100k); Plus £14.99/month (no limit); Premium £39.99/month |
| Share dealing | Not available (funds and Vanguard ETFs only) | £3.99 per trade (£2.99 on Premium) |
| Fund dealing | Free | £3.99 per trade (£2.99 on Premium) |
| FX fee | None (GBP funds) | 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 | £100/month or £500 lump sum | No minimum (£25/month for regular investing) |
Long-term investors praise the low fund costs and the simplicity of LifeStrategy portfolios.
The £4 minimum monthly fee frustrated smaller investors when it landed, and some reviews mention slow customer service.
Read Vanguard 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 TrustpilotVanguard UK is the default answer for one-fund index investing. If your plan is a LifeStrategy or FTSE Global All Cap fund and nothing else, the combination of cheap funds and a capped 0.15% platform fee is excellent, especially above £32,000.
Below £32,000 the £4 monthly minimum changes the maths, and a free platform like Trading 212 or Prosper holding a similar Vanguard ETF can work out cheaper. You also cannot hold individual shares or other fund managers' products.
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.
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.